1
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Rühle T, Leister D, Pasch V. Chloroplast ATP synthase: From structure to engineering. THE PLANT CELL 2024; 36:3974-3996. [PMID: 38484126 PMCID: PMC11449085 DOI: 10.1093/plcell/koae081] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2023] [Accepted: 12/27/2023] [Indexed: 10/05/2024]
Abstract
F-type ATP synthases are extensively researched protein complexes because of their widespread and central role in energy metabolism. Progress in structural biology, proteomics, and molecular biology has also greatly advanced our understanding of the catalytic mechanism, post-translational modifications, and biogenesis of chloroplast ATP synthases. Given their critical role in light-driven ATP generation, tailoring the activity of chloroplast ATP synthases and modeling approaches can be applied to modulate photosynthesis. In the future, advances in genetic manipulation and protein design tools will significantly expand the scope for testing new strategies in engineering light-driven nanomotors.
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Affiliation(s)
- Thilo Rühle
- Plant Molecular Biology, Faculty of Biology, Ludwig-Maximilians-University Munich, D-82152 Planegg-Martinsried, Germany
| | - Dario Leister
- Plant Molecular Biology, Faculty of Biology, Ludwig-Maximilians-University Munich, D-82152 Planegg-Martinsried, Germany
| | - Viviana Pasch
- Plant Molecular Biology, Faculty of Biology, Ludwig-Maximilians-University Munich, D-82152 Planegg-Martinsried, Germany
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2
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Wu Y, Cui Y, Li D, Yin M, Pei Y, Wang X, Li J, Zhu Y. Fulvic acid mediated highly efficient heterotrophic nitrification-aerobic denitrification by Paracoccus denitrificans XW11 with reduced C/N ratio. WATER RESEARCH 2024; 267:122557. [PMID: 39366321 DOI: 10.1016/j.watres.2024.122557] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2024] [Revised: 09/18/2024] [Accepted: 09/29/2024] [Indexed: 10/06/2024]
Abstract
Reducing the C/N ratio requirements for heterotrophic nitrification-aerobic denitrification (HNAD) is crucial for its practical application; however, it remains underexplored. In this study, a highly efficient HNAD bacterium, Paracoccus denitrificans XW11, was isolated. The HNAD characteristics of XW11 were studied, and the redox mediator fulvic acid (FA) was used to reduce the C/N requirements. Whole-genome sequencing revealed multiple denitrification genes in XW11; however, nitrification genes were not identified, because heterotrophic nitrification-related gene sequences were not included in the database. However, the nitrogen removal related enzyme activity test revealed complete nitrification and denitrification pathways. Reverse transcription PCR showed that the membrane-bound nitrate reductase (NarG), rather than the periplasmic nitrate reductase, was responsible for aerobic denitrification. The conventional nitrite reductase (NirS) also does not mediate nitrite denitrification. When the C/N ratio was 10, the ammonia removal efficiency of the Control was 71.71 % and the addition of FA increased it to 86.12 %. Transcriptomic analysis indicated electron flow from the carbon source to FA without proton transmembrane transport, and the presence of FA constructs another electron transfer system. The redox potential of oxidized FA/reduced FA is 0.3679 V, avoiding competition for electrons from Complex III. Thus, ammonia monooxygenase obtains electrons more easily, thereby promoting nitrification. The enzyme activity test of the nitrification process confirmed this view. In addition, NarG expression increased, and the denitrification process was enhanced. Overall, FA improved HNAD efficiency by facilitating electron transfer to the nitrogen dissimilation process, offering a novel approach to reduce the C/N requirement of HNAD.
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Affiliation(s)
- Yaodong Wu
- National Engineering Laboratory for Advanced Municipal Wastewater Treatment and Reuse Technology, Beijing University of Technology, Beijing 100124, China
| | - Yanan Cui
- National Engineering Laboratory for Advanced Municipal Wastewater Treatment and Reuse Technology, Beijing University of Technology, Beijing 100124, China
| | - Dongyue Li
- National Engineering Laboratory for Advanced Municipal Wastewater Treatment and Reuse Technology, Beijing University of Technology, Beijing 100124, China
| | - Muchen Yin
- National Engineering Laboratory for Advanced Municipal Wastewater Treatment and Reuse Technology, Beijing University of Technology, Beijing 100124, China
| | - Yanxue Pei
- National Engineering Laboratory for Advanced Municipal Wastewater Treatment and Reuse Technology, Beijing University of Technology, Beijing 100124, China
| | - Xiujie Wang
- The College of environmental and chemical engineering, Jiangsu University of Science and Technology, Zhenjiang 212100, China
| | - Jun Li
- National Engineering Laboratory for Advanced Municipal Wastewater Treatment and Reuse Technology, Beijing University of Technology, Beijing 100124, China.
| | - Yuhan Zhu
- National Engineering Laboratory for Advanced Municipal Wastewater Treatment and Reuse Technology, Beijing University of Technology, Beijing 100124, China
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3
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Gerle C, Jiko C, Nakano A, Yokoyama K, Gopalasingam CC, Shigematsu H, Abe K. Human F-ATP synthase as a drug target. Pharmacol Res 2024; 209:107423. [PMID: 39303772 DOI: 10.1016/j.phrs.2024.107423] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/18/2024] [Revised: 09/14/2024] [Accepted: 09/16/2024] [Indexed: 09/22/2024]
Abstract
Practical and conceptual barriers have kept human F-ATP synthase out of reach as a target for the treatment of human diseases. Although this situation has persisted for decades, it may change in the near future. In this review the principal functionalities of human F-ATP synthase--proton motive force / ATP interconversion, membrane bending and mitochondrial permeability transition--are surveyed in the context of their respective potential for pharmaceutical intervention. Further, the technical requirements necessary to allow drug designs that are effective at the multiple levels of functionality and modality of human F-ATP synthase are discussed. The structure-based development of gastric proton pump inhibitors is used to exemplify what might be feasible for human F-ATP synthase. And finally, four structural regions of the human F-ATP synthase are examined as potential sites for the development of structure based drug development.
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Affiliation(s)
- Christoph Gerle
- Life Science Research Infrastructure Group, RIKEN SPring-8 Center, Kouto, 1-1-1, Sayo, Hyogo, Japan.
| | - Chimari Jiko
- Division of Radiation Life Science, Institute for Integrated Radiation and Nuclear Science, Kyoto University, Osaka, Japan
| | - Atsuki Nakano
- Department of Molecular Biosciences, Kyoto Sangyo University, Kamigamo-Motoyama, Kyoto 603-8555, Japan
| | - Ken Yokoyama
- Department of Molecular Biosciences, Kyoto Sangyo University, Kamigamo-Motoyama, Kyoto 603-8555, Japan
| | - Chai C Gopalasingam
- Life Science Research Infrastructure Group, RIKEN SPring-8 Center, Kouto, 1-1-1, Sayo, Hyogo, Japan
| | - Hideki Shigematsu
- Structural Biology Division, Japan Synchrotron Radiation Research Institute, SPring-8, Sayo, Hyogo, Japan
| | - Kazuhiro Abe
- Molecular Biochemistry Lab, Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo 060-0810, Japan
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4
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Dietrich L, Agip ANA, Kunz C, Schwarz A, Kühlbrandt W. In situ structure and rotary states of mitochondrial ATP synthase in whole Polytomella cells. Science 2024; 385:1086-1090. [PMID: 39236170 DOI: 10.1126/science.adp4640] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2024] [Accepted: 07/31/2024] [Indexed: 09/07/2024]
Abstract
Cells depend on a continuous supply of adenosine triphosphate (ATP), the universal energy currency. In mitochondria, ATP is produced by a series of redox reactions, whereby an electrochemical gradient is established across the inner mitochondrial membrane. The ATP synthase harnesses the energy of the gradient to generate ATP from adenosine diphosphate (ADP) and inorganic phosphate. We determined the structure of ATP synthase within mitochondria of the unicellular flagellate Polytomella by electron cryo-tomography and subtomogram averaging at up to 4.2-angstrom resolution, revealing six rotary positions of the central stalk, subclassified into 21 substates of the F1 head. The Polytomella ATP synthase forms helical arrays with multiple adjacent rows defining the cristae ridges. The structure of ATP synthase under native operating conditions in the presence of a membrane potential represents a pivotal step toward the analysis of membrane protein complexes in situ.
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Affiliation(s)
- Lea Dietrich
- Department of Structural Biology, Max Planck Institute of Biophysics, 60438 Frankfurt, Germany
| | - Ahmed-Noor A Agip
- Department of Structural Biology, Max Planck Institute of Biophysics, 60438 Frankfurt, Germany
| | - Christina Kunz
- Department of Structural Biology, Max Planck Institute of Biophysics, 60438 Frankfurt, Germany
| | - Andre Schwarz
- Department of Synaptic Plasticity, Max Planck Institute for Brain Research, 60438 Frankfurt, Germany
| | - Werner Kühlbrandt
- Department of Structural Biology, Max Planck Institute of Biophysics, 60438 Frankfurt, Germany
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5
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Silverstein TP. Oxidative Phosphorylation Does Not Violate the Second Law of Thermodynamics. J Phys Chem B 2024; 128:8448-8458. [PMID: 39167050 PMCID: PMC11382260 DOI: 10.1021/acs.jpcb.4c03047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/23/2024]
Abstract
In a recent series of papers, James W. Lee reported that mitochondrial oxidative phosphorylation violates the second law of thermodynamics and that it is allowed to do so because it is a "Type-B" process that features lateral and longitudinal membrane asymmetry. We show here that these contentions are based on problematic interpretations of the literature. More reliable values of ΔGredox and ΔGATP synthesis show that the second law is not violated. More recent reports on the structures of the redox-driven proton pumps (Complexes I, III, and IV) suggest that longitudinal membrane asymmetry does not exist. Finally, Lee's predictions for the concentration of protons localized at the P-side surface of the bioenergetic membrane are likely to be much too high due to several errors; thus, his predicted high values of ΔpHsurface that violate the second law are likely to be wrong. There is currently no strong experimental or theoretical evidence to support the contention that oxidative phosphorylation violates the second law of thermodynamics.
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Affiliation(s)
- Todd P Silverstein
- Department of Chemistry (emeritus), Willamette University, Salem, Oregon 97301,United States
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6
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Ramanthrikkovil Variyam A, Rzycki M, Yucknovsky A, Stuchebrukhov AA, Drabik D, Amdursky N. Proton diffusion on the surface of mixed lipid membranes highlights the role of membrane composition. Biophys J 2024:S0006-3495(24)00441-7. [PMID: 38961623 DOI: 10.1016/j.bpj.2024.07.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2024] [Revised: 06/13/2024] [Accepted: 07/01/2024] [Indexed: 07/05/2024] Open
Abstract
Proton circuits within biological membranes, the foundation of natural bioenergetic systems, are significantly influenced by the lipid compositions of different biological membranes. In this study, we investigate the influence of mixed lipid membrane composition on the proton transfer (PT) properties on the surface of the membrane. We track the excited-state PT (ESPT) process from a tethered probe to the membrane with timescales and length scales of PT relevant to bioenergetic systems. Two processes can happen during ESPT: the initial PT from the probe to the membrane at short timescales, followed by diffusion of dissociated protons around the probe on the membrane, and the possible geminate recombination with the probe at longer timescales. Here, we use membranes composed of mixtures of phosphatidylcholine (PC) and phosphatidic acid (PA). We show that the changes in the ESPT properties are not monotonous with the concentration of the lipid mixture; at a low concentration of PA in PC, we find that the membrane is a poor proton acceptor. Molecular dynamics simulations indicate that the membrane is more structured at this specific lipid mixture, with the least number of defects. Accordingly, we suggest that the structure of the membrane is an important factor in facilitating PT. We further show that the composition of the membrane affects the geminate proton diffusion around the probe, whereas, on a timescale of tens of nanoseconds, the dissociated proton is mostly lateral restricted to the membrane plane in PA membranes, while in PC, the diffusion is less restricted by the membrane.
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Affiliation(s)
| | - Mateusz Rzycki
- Department of Biomedical Engineering, Wroclaw University of Science and Technology, Wroclaw, Poland
| | - Anna Yucknovsky
- Schulich Faculty of Chemistry, Technion - Israel Institute of Technology, Haifa, Israel
| | | | - Dominik Drabik
- Department of Biomedical Engineering, Wroclaw University of Science and Technology, Wroclaw, Poland
| | - Nadav Amdursky
- Schulich Faculty of Chemistry, Technion - Israel Institute of Technology, Haifa, Israel.
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7
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Lee C, Wallace DC, Burke PJ. Super-Resolution Imaging of Voltages in the Interior of Individual, Vital Mitochondria. ACS NANO 2024; 18:1345-1356. [PMID: 37289571 PMCID: PMC10795477 DOI: 10.1021/acsnano.3c02768] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2023] [Accepted: 06/02/2023] [Indexed: 06/10/2023]
Abstract
We present super-resolution microscopy of isolated functional mitochondria, enabling real-time studies of structure and function (voltages) in response to pharmacological manipulation. Changes in mitochondrial membrane potential as a function of time and position can be imaged in different metabolic states (not possible in whole cells), created by the addition of substrates and inhibitors of the electron transport chain, enabled by the isolation of vital mitochondria. By careful analysis of structure dyes and voltage dyes (lipophilic cations), we demonstrate that most of the fluorescent signal seen from voltage dyes is due to membrane bound dyes, and develop a model for the membrane potential dependence of the fluorescence contrast for the case of super-resolution imaging, and how it relates to membrane potential. This permits direct analysis of mitochondrial structure and function (voltage) of isolated, individual mitochondria as well as submitochondrial structures in the functional, intact state, a major advance in super-resolution studies of living organelles.
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Affiliation(s)
- ChiaHung Lee
- Department
of Electrical Engineering and Computer Science, Department of Biomedical
Engineering, University of California, Irvine, California 92697, United States
| | - Douglas C. Wallace
- Center
for Mitochondrial and Epigenomic Medicine, Children’s Hospital
of Philadelphia and Department of Pediatrics, Division of Human Genetics, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Peter J. Burke
- Department
of Electrical Engineering and Computer Science, Department of Biomedical
Engineering, University of California, Irvine, California 92697, United States
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8
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Braun HP, Klusch N. Promotion of oxidative phosphorylation by complex I-anchored carbonic anhydrases? TRENDS IN PLANT SCIENCE 2024; 29:64-71. [PMID: 37599162 DOI: 10.1016/j.tplants.2023.07.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2023] [Revised: 07/12/2023] [Accepted: 07/19/2023] [Indexed: 08/22/2023]
Abstract
The mitochondrial NADH-dehydrogenase complex of the respiratory chain, known as complex I, includes a carbonic anhydrase (CA) module attached to its membrane arm on the matrix side in protozoans, algae, and plants. Its physiological role is so far unclear. Recent electron cryo-microscopy (cryo-EM) structures show that the CA module may directly provide protons for translocation across the inner mitochondrial membrane at complex I. CAs can have a central role in adjusting the proton concentration in the mitochondrial matrix. We suggest that CA anchoring in complex I represents the original configuration to secure oxidative phosphorylation (OXPHOS) in the context of early endosymbiosis. After development of 'modern mitochondria' with pronounced cristae structures, this anchoring became dispensable, but has been retained in protozoans, algae, and plants.
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Affiliation(s)
- Hans-Peter Braun
- Institute of Plant Genetics, Leibniz Universität Hannover, Herrenhäuser Str. 2, 30419 Hannover, Germany.
| | - Niklas Klusch
- Department of Structural Biology, Max-Planck-Institute of Biophysics, Max-von-Laue-Straße 3, 60438 Frankfurt, Germany.
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9
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Venkatraman K, Lee CT, Garcia GC, Mahapatra A, Milshteyn D, Perkins G, Kim K, Pasolli HA, Phan S, Lippincott‐Schwartz J, Ellisman MH, Rangamani P, Budin I. Cristae formation is a mechanical buckling event controlled by the inner mitochondrial membrane lipidome. EMBO J 2023; 42:e114054. [PMID: 37933600 PMCID: PMC10711667 DOI: 10.15252/embj.2023114054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2023] [Revised: 10/16/2023] [Accepted: 10/18/2023] [Indexed: 11/08/2023] Open
Abstract
Cristae are high-curvature structures in the inner mitochondrial membrane (IMM) that are crucial for ATP production. While cristae-shaping proteins have been defined, analogous lipid-based mechanisms have yet to be elucidated. Here, we combine experimental lipidome dissection with multi-scale modeling to investigate how lipid interactions dictate IMM morphology and ATP generation. When modulating phospholipid (PL) saturation in engineered yeast strains, we observed a surprisingly abrupt breakpoint in IMM topology driven by a continuous loss of ATP synthase organization at cristae ridges. We found that cardiolipin (CL) specifically buffers the inner mitochondrial membrane against curvature loss, an effect that is independent of ATP synthase dimerization. To explain this interaction, we developed a continuum model for cristae tubule formation that integrates both lipid and protein-mediated curvatures. This model highlighted a snapthrough instability, which drives IMM collapse upon small changes in membrane properties. We also showed that cardiolipin is essential in low-oxygen conditions that promote PL saturation. These results demonstrate that the mechanical function of cardiolipin is dependent on the surrounding lipid and protein components of the IMM.
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Affiliation(s)
- Kailash Venkatraman
- Department of Chemistry and BiochemistryUniversity of California San DiegoLa JollaCAUSA
| | - Christopher T Lee
- Department of Mechanical and Aerospace EngineeringUniversity of California San DiegoLa JollaCAUSA
| | - Guadalupe C Garcia
- Computational Neurobiology LaboratorySalk Institute for Biological StudiesLa JollaCAUSA
| | - Arijit Mahapatra
- Department of Mechanical and Aerospace EngineeringUniversity of California San DiegoLa JollaCAUSA
- Present address:
Applied Physical SciencesUniversity of North Carolina Chapel HillChapel HillNCUSA
| | - Daniel Milshteyn
- Department of Chemistry and BiochemistryUniversity of California San DiegoLa JollaCAUSA
| | - Guy Perkins
- National Center for Microscopy and Imaging Research, Center for Research in Biological SystemsUniversity of California San DiegoLa JollaCAUSA
| | - Keun‐Young Kim
- National Center for Microscopy and Imaging Research, Center for Research in Biological SystemsUniversity of California San DiegoLa JollaCAUSA
| | - H Amalia Pasolli
- Howard Hughes Medical InstituteAshburnVAUSA
- Present address:
Electron Microscopy Resource CenterThe Rockefeller UniversityNew YorkNYUSA
| | - Sebastien Phan
- National Center for Microscopy and Imaging Research, Center for Research in Biological SystemsUniversity of California San DiegoLa JollaCAUSA
| | | | - Mark H Ellisman
- National Center for Microscopy and Imaging Research, Center for Research in Biological SystemsUniversity of California San DiegoLa JollaCAUSA
| | - Padmini Rangamani
- Department of Mechanical and Aerospace EngineeringUniversity of California San DiegoLa JollaCAUSA
| | - Itay Budin
- Department of Chemistry and BiochemistryUniversity of California San DiegoLa JollaCAUSA
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10
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Knyazev DG, Silverstein TP, Brescia S, Maznichenko A, Pohl P. A New Theory about Interfacial Proton Diffusion Revisited: The Commonly Accepted Laws of Electrostatics and Diffusion Prevail. Biomolecules 2023; 13:1641. [PMID: 38002323 PMCID: PMC10669390 DOI: 10.3390/biom13111641] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2023] [Revised: 11/02/2023] [Accepted: 11/07/2023] [Indexed: 11/26/2023] Open
Abstract
The high propensity of protons to stay at interfaces has attracted much attention over the decades. It enables long-range interfacial proton diffusion without relying on titratable residues or electrostatic attraction. As a result, various phenomena manifest themselves, ranging from spillover in material sciences to local proton circuits between proton pumps and ATP synthases in bioenergetics. In an attempt to replace all existing theoretical and experimental insight into the origin of protons' preference for interfaces, TELP, the "Transmembrane Electrostatically-Localized Protons" hypothesis, has been proposed. The TELP hypothesis envisions static H+ and OH- layers on opposite sides of interfaces that are up to 75 µm thick. Yet, the separation at which the electrostatic interaction between two elementary charges is comparable in magnitude to the thermal energy is more than two orders of magnitude smaller and, as a result, the H+ and OH- layers cannot mutually stabilize each other, rendering proton accumulation at the interface energetically unfavorable. We show that (i) the law of electroneutrality, (ii) Fick's law of diffusion, and (iii) Coulomb's law prevail. Using them does not hinder but helps to interpret previously published experimental results, and also helps us understand the high entropy release barrier enabling long-range proton diffusion along the membrane surface.
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Affiliation(s)
- Denis G. Knyazev
- Institute of Biophysics, Johannes Kepler University, 4020 Linz, Austria; (D.G.K.); (S.B.); (A.M.)
| | | | - Stefania Brescia
- Institute of Biophysics, Johannes Kepler University, 4020 Linz, Austria; (D.G.K.); (S.B.); (A.M.)
| | - Anna Maznichenko
- Institute of Biophysics, Johannes Kepler University, 4020 Linz, Austria; (D.G.K.); (S.B.); (A.M.)
| | - Peter Pohl
- Institute of Biophysics, Johannes Kepler University, 4020 Linz, Austria; (D.G.K.); (S.B.); (A.M.)
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11
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Semenov AY, Tikhonov AN. Electrometric and Electron Paramagnetic Resonance Measurements of a Difference in the Transmembrane Electrochemical Potential: Photosynthetic Subcellular Structures and Isolated Pigment-Protein Complexes. MEMBRANES 2023; 13:866. [PMID: 37999352 PMCID: PMC10673362 DOI: 10.3390/membranes13110866] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2023] [Revised: 10/23/2023] [Accepted: 10/26/2023] [Indexed: 11/25/2023]
Abstract
A transmembrane difference in the electrochemical potentials of protons (ΔμH+) serves as a free energy intermediate in energy-transducing organelles of the living cell. The contributions of two components of the ΔμH+ (electrical, Δψ, and concentrational, ΔpH) to the overall ΔμH+ value depend on the nature and lipid composition of the energy-coupling membrane. In this review, we briefly consider several of the most common instrumental (electrometric and EPR) methods for numerical estimations of Δψ and ΔpH. In particular, the kinetics of the flash-induced electrometrical measurements of Δψ in bacterial chromatophores, isolated bacterial reaction centers, and Photosystems I and II of the oxygenic photosynthesis, as well as the use of pH-sensitive molecular indicators and kinetic data regarding pH-dependent electron transport in chloroplasts, have been reviewed. Further perspectives on the application of these methods to solve some fundamental and practical problems of membrane bioenergetics are discussed.
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Affiliation(s)
- Alexey Yu. Semenov
- A.N. Belozersky Institute of Physical-Chemical Biology, M.V. Lomonosov Moscow State University, 119991 Moscow, Russia;
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12
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Ježek P, Jabůrek M, Holendová B, Engstová H, Dlasková A. Mitochondrial Cristae Morphology Reflecting Metabolism, Superoxide Formation, Redox Homeostasis, and Pathology. Antioxid Redox Signal 2023; 39:635-683. [PMID: 36793196 PMCID: PMC10615093 DOI: 10.1089/ars.2022.0173] [Citation(s) in RCA: 21] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/24/2022] [Revised: 02/08/2023] [Accepted: 02/09/2023] [Indexed: 02/17/2023]
Abstract
Significance: Mitochondrial (mt) reticulum network in the cell possesses amazing ultramorphology of parallel lamellar cristae, formed by the invaginated inner mitochondrial membrane. Its non-invaginated part, the inner boundary membrane (IBM) forms a cylindrical sandwich with the outer mitochondrial membrane (OMM). Crista membranes (CMs) meet IBM at crista junctions (CJs) of mt cristae organizing system (MICOS) complexes connected to OMM sorting and assembly machinery (SAM). Cristae dimensions, shape, and CJs have characteristic patterns for different metabolic regimes, physiological and pathological situations. Recent Advances: Cristae-shaping proteins were characterized, namely rows of ATP-synthase dimers forming the crista lamella edges, MICOS subunits, optic atrophy 1 (OPA1) isoforms and mitochondrial genome maintenance 1 (MGM1) filaments, prohibitins, and others. Detailed cristae ultramorphology changes were imaged by focused-ion beam/scanning electron microscopy. Dynamics of crista lamellae and mobile CJs were demonstrated by nanoscopy in living cells. With tBID-induced apoptosis a single entirely fused cristae reticulum was observed in a mitochondrial spheroid. Critical Issues: The mobility and composition of MICOS, OPA1, and ATP-synthase dimeric rows regulated by post-translational modifications might be exclusively responsible for cristae morphology changes, but ion fluxes across CM and resulting osmotic forces might be also involved. Inevitably, cristae ultramorphology should reflect also mitochondrial redox homeostasis, but details are unknown. Disordered cristae typically reflect higher superoxide formation. Future Directions: To link redox homeostasis to cristae ultramorphology and define markers, recent progress will help in uncovering mechanisms involved in proton-coupled electron transfer via the respiratory chain and in regulation of cristae architecture, leading to structural determination of superoxide formation sites and cristae ultramorphology changes in diseases. Antioxid. Redox Signal. 39, 635-683.
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Affiliation(s)
- Petr Ježek
- Department No. 75, Institute of Physiology, Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | - Martin Jabůrek
- Department No. 75, Institute of Physiology, Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | - Blanka Holendová
- Department No. 75, Institute of Physiology, Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | - Hana Engstová
- Department No. 75, Institute of Physiology, Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | - Andrea Dlasková
- Department No. 75, Institute of Physiology, Academy of Sciences of the Czech Republic, Prague, Czech Republic
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13
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Li Z, Yu F, Xu X, Wang T, Fei J, Hao J, Li J. Photozyme-Catalyzed ATP Generation Based on ATP Synthase-Reconstituted Nanoarchitectonics. J Am Chem Soc 2023; 145:20907-20912. [PMID: 37606591 DOI: 10.1021/jacs.3c06090] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/23/2023]
Abstract
We demonstrate that ATP synthase-reconstituted proteoliposome coatings on the surface of microcapsules can realize photozyme-catalyzed oxidative phosphorylation. The microcapsules were assembled through layer-by-layer deposition of semiconducting graphitic carbon nitride (g-C3N4) nanosheets and polyelectrolytes. It is found that electrons from polyelectrolytes are transferred to g-C3N4 nanosheets, which enhances the separation of photogenerated electron-hole pairs. Thus, the encapsulated g-C3N4 nanosheets as the photozyme accelerate oxidation of glucose into gluconic acid to yield protons under light illumination. The outward transmembrane proton gradient is established to drive ATP synthase to synthesize adenosine triphosphate. With such an assembled system, light-driven oxidative phosphorylation is achieved. This indicates that an assembled photozyme can be used for oxidative phosphorylation, which creates an unusual way for chemical-to-biological energy conversion. Compared to conventional oxidative phosphorylation systems, such an artificial design enables higher energy conversion efficiency.
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Affiliation(s)
- Zibo Li
- Beijing National Laboratory for Molecular Sciences (BNLMS), CAS Key Lab of Colloid, Interface and Chemical Thermodynamics, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
- Key Laboratory of Colloid and Interface Chemistry of the Ministry of Education, School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100, China
| | - Fanchen Yu
- Beijing National Laboratory for Molecular Sciences (BNLMS), CAS Key Lab of Colloid, Interface and Chemical Thermodynamics, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xia Xu
- Beijing National Laboratory for Molecular Sciences (BNLMS), CAS Key Lab of Colloid, Interface and Chemical Thermodynamics, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Tonghui Wang
- Beijing National Laboratory for Molecular Sciences (BNLMS), CAS Key Lab of Colloid, Interface and Chemical Thermodynamics, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jinbo Fei
- Beijing National Laboratory for Molecular Sciences (BNLMS), CAS Key Lab of Colloid, Interface and Chemical Thermodynamics, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jingcheng Hao
- Key Laboratory of Colloid and Interface Chemistry of the Ministry of Education, School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100, China
| | - Junbai Li
- Beijing National Laboratory for Molecular Sciences (BNLMS), CAS Key Lab of Colloid, Interface and Chemical Thermodynamics, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
- University of Chinese Academy of Sciences, Beijing 100049, China
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14
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Venkatraman K, Lee CT, Garcia GC, Mahapatra A, Milshteyn D, Perkins G, Kim KY, Pasolli HA, Phan S, Lippincott-Schwartz J, Ellisman MH, Rangamani P, Budin I. Cristae formation is a mechanical buckling event controlled by the inner membrane lipidome. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.13.532310. [PMID: 36993370 PMCID: PMC10054968 DOI: 10.1101/2023.03.13.532310] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 04/28/2023]
Abstract
Cristae are high curvature structures in the inner mitochondrial membrane (IMM) that are crucial for ATP production. While cristae-shaping proteins have been defined, analogous mechanisms for lipids have yet to be elucidated. Here we combine experimental lipidome dissection with multi-scale modeling to investigate how lipid interactions dictate IMM morphology and ATP generation. When modulating phospholipid (PL) saturation in engineered yeast strains, we observed a surprisingly abrupt breakpoint in IMM topology driven by a continuous loss of ATP synthase organization at cristae ridges. We found that cardiolipin (CL) specifically buffers the IMM against curvature loss, an effect that is independent of ATP synthase dimerization. To explain this interaction, we developed a continuum model for cristae tubule formation that integrates both lipid and protein-mediated curvatures. The model highlighted a snapthrough instability, which drives IMM collapse upon small changes in membrane properties. We also showed that CL is essential in low oxygen conditions that promote PL saturation. These results demonstrate that the mechanical function of CL is dependent on the surrounding lipid and protein components of the IMM.
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Affiliation(s)
- Kailash Venkatraman
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, CA 92093
| | - Christopher T Lee
- Department of Mechanical and Aerospace Engineering, University of California San Diego, La Jolla, CA 92093
| | - Guadalupe C Garcia
- Computational Neurobiology Laboratory, Salk Institute for Biological Studies, La Jolla CA 92097
| | - Arijit Mahapatra
- Department of Mechanical and Aerospace Engineering, University of California San Diego, La Jolla, CA 92093
| | - Daniel Milshteyn
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, CA 92093
| | - Guy Perkins
- National Center for Microscopy and Imaging Research, Center for Research in Biological Systems, University of California San Diego, La Jolla, CA 92093
| | - Keun-Young Kim
- National Center for Microscopy and Imaging Research, Center for Research in Biological Systems, University of California San Diego, La Jolla, CA 92093
| | - H Amalia Pasolli
- Howard Hughes Medical Institute, Janelia Research Campus, Ashburn VA 20147
| | - Sebastien Phan
- National Center for Microscopy and Imaging Research, Center for Research in Biological Systems, University of California San Diego, La Jolla, CA 92093
| | | | - Mark H Ellisman
- National Center for Microscopy and Imaging Research, Center for Research in Biological Systems, University of California San Diego, La Jolla, CA 92093
| | - Padmini Rangamani
- Department of Mechanical and Aerospace Engineering, University of California San Diego, La Jolla, CA 92093
| | - Itay Budin
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, CA 92093
- Lead contact
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15
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Adams RA, Liu Z, Hsieh C, Marko M, Lederer WJ, Jafri MS, Mannella C. Structural Analysis of Mitochondria in Cardiomyocytes: Insights into Bioenergetics and Membrane Remodeling. Curr Issues Mol Biol 2023; 45:6097-6115. [PMID: 37504301 PMCID: PMC10378267 DOI: 10.3390/cimb45070385] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2023] [Revised: 07/15/2023] [Accepted: 07/18/2023] [Indexed: 07/29/2023] Open
Abstract
Mitochondria in mammalian cardiomyocytes display considerable structural heterogeneity, the significance of which is not currently understood. We use electron microscopic tomography to analyze a dataset of 68 mitochondrial subvolumes to look for correlations among mitochondrial size and shape, crista morphology and membrane density, and organelle location within rat cardiac myocytes. A tomographic analysis guided the definition of four classes of crista morphology: lamellar, tubular, mixed and transitional, the last associated with remodeling between lamellar and tubular cristae. Correlations include an apparent bias for mitochondria with lamellar cristae to be located in the regions between myofibrils and a two-fold larger crista membrane density in mitochondria with lamellar cristae relative to mitochondria with tubular cristae. The examination of individual cristae inside mitochondria reveals local variations in crista topology, such as extent of branching, alignment of fenestrations and progressive changes in membrane morphology and packing density. The findings suggest both a rationale for the interfibrillar location of lamellar mitochondria and a pathway for crista remodeling from lamellar to tubular morphology.
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Affiliation(s)
- Raquel A. Adams
- Krasnow Institute for Advanced Study and School of Systems Biology, George Mason University, Fairfax, VA 22030, USA;
| | - Zheng Liu
- Wadsworth Center, New York State Department of Health, Albany, NY 12201, USA (M.M.)
| | - Chongere Hsieh
- Wadsworth Center, New York State Department of Health, Albany, NY 12201, USA (M.M.)
| | - Michael Marko
- Wadsworth Center, New York State Department of Health, Albany, NY 12201, USA (M.M.)
| | - W. Jonathan Lederer
- Department of Physiology, School of Medicine, University of Maryland, Baltimore, MD 21201, USA;
- Center for Biomedical Engineering and Technology, School of Medicine, University of Maryland, Baltimore, MD 21201, USA
| | - M. Saleet Jafri
- Krasnow Institute for Advanced Study and School of Systems Biology, George Mason University, Fairfax, VA 22030, USA;
- Center for Biomedical Engineering and Technology, School of Medicine, University of Maryland, Baltimore, MD 21201, USA
| | - Carmen Mannella
- Department of Physiology, School of Medicine, University of Maryland, Baltimore, MD 21201, USA;
- Center for Biomedical Engineering and Technology, School of Medicine, University of Maryland, Baltimore, MD 21201, USA
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16
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Mendes TV, Ranft J, Berthoumieux H. Model of membrane deformations driven by a surface pH gradient. Phys Rev E 2023; 108:014113. [PMID: 37583220 DOI: 10.1103/physreve.108.014113] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Accepted: 06/06/2023] [Indexed: 08/17/2023]
Abstract
Many cellular organelles are membrane-bound structures with complex membrane composition and shape. Their shapes have been observed to depend on the metabolic state of the organelle and the mechanisms that couple biochemical pathways and membrane shape are still actively investigated. Here, we study a model coupling inhomogeneities in the lipid composition and membrane geometry via a generalized Helfrich free energy. We derive the resulting stress tensor, the Green's function for a tubular membrane, and compute the phase diagram of the induced deformations. We then apply this model to study the deformation of mitochondria cristae described as membrane tubes supporting a pH gradient at its surface. This gradient in turn controls the lipid composition of the membrane via the protonation or deprotonation of cardiolipins, which are acid-based lipids known to be crucial for mitochondria shape and functioning. Our model predicts the appearance of tube deformations resembling the observed shape changes of cristea when submitted to a proton gradient.
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Affiliation(s)
- Toni V Mendes
- Laboratoire Ondes et Matière d'Aquitaine, Université de Bordeaux, Unité Mixte de Recherche 5798, CNRS, F-33400 Talence, France
- Sorbonne Université, CNRS, Laboratoire de Physique Théorique de la Matière Condensée (LPTMC, UMR 7600), F-75005 Paris, France
| | - Jonas Ranft
- Institut de Biologie de l'ENS, Ecole Normale Supérieure, CNRS, Inserm, Université PSL, 46 rue d'Ulm, F-75005 Paris, France
| | - Hélène Berthoumieux
- Sorbonne Université, CNRS, Laboratoire de Physique Théorique de la Matière Condensée (LPTMC, UMR 7600), F-75005 Paris, France
- Fachbereich Physik, Freie Universität Berlin, Arnimallee 14, Berlin 14195, Germany
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17
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Greiser M, Karbowski M, Kaplan AD, Coleman AK, Verhoeven N, Mannella CA, Lederer WJ, Boyman L. Calcium and bicarbonate signaling pathways have pivotal, resonating roles in matching ATP production to demand. eLife 2023; 12:e84204. [PMID: 37272417 PMCID: PMC10284600 DOI: 10.7554/elife.84204] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Accepted: 06/01/2023] [Indexed: 06/06/2023] Open
Abstract
Mitochondrial ATP production in ventricular cardiomyocytes must be continually adjusted to rapidly replenish the ATP consumed by the working heart. Two systems are known to be critical in this regulation: mitochondrial matrix Ca2+ ([Ca2+]m) and blood flow that is tuned by local cardiomyocyte metabolic signaling. However, these two regulatory systems do not fully account for the physiological range of ATP consumption observed. We report here on the identity, location, and signaling cascade of a third regulatory system -- CO2/bicarbonate. CO2 is generated in the mitochondrial matrix as a metabolic waste product of the oxidation of nutrients. It is a lipid soluble gas that rapidly permeates the inner mitochondrial membrane and produces bicarbonate in a reaction accelerated by carbonic anhydrase. The bicarbonate level is tracked physiologically by a bicarbonate-activated soluble adenylyl cyclase (sAC). Using structural Airyscan super-resolution imaging and functional measurements we find that sAC is primarily inside the mitochondria of ventricular cardiomyocytes where it generates cAMP when activated by bicarbonate. Our data strongly suggest that ATP production in these mitochondria is regulated by this cAMP signaling cascade operating within the inter-membrane space by activating local EPAC1 (Exchange Protein directly Activated by cAMP) which turns on Rap1 (Ras-related protein-1). Thus, mitochondrial ATP production is increased by bicarbonate-triggered sAC-signaling through Rap1. Additional evidence is presented indicating that the cAMP signaling itself does not occur directly in the matrix. We also show that this third signaling process involving bicarbonate and sAC activates the mitochondrial ATP production machinery by working independently of, yet in conjunction with, [Ca2+]m-dependent ATP production to meet the energy needs of cellular activity in both health and disease. We propose that the bicarbonate and calcium signaling arms function in a resonant or complementary manner to match mitochondrial ATP production to the full range of energy consumption in ventricular cardiomyocytes.
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Affiliation(s)
- Maura Greiser
- Center for Biomedical Engineering and Technology, University of Maryland School of MedicineBaltimoreUnited States
- Department of Physiology, University of Marylan School of MedicineBaltimoreUnited States
- Claude D. Pepper Older Americans Independence Center, University of Maryland School of MedicineBaltimoreUnited States
| | - Mariusz Karbowski
- Center for Biomedical Engineering and Technology, University of Maryland School of MedicineBaltimoreUnited States
- Department of Biochemistry and Molecular Biology, University of Maryland School of MedicineBaltimoreUnited States
- Marlene and Stewart Greenebaum Comprehensive Cancer Center, University of Maryland Baltimore School of MedicineBaltimoreUnited States
| | - Aaron David Kaplan
- Center for Biomedical Engineering and Technology, University of Maryland School of MedicineBaltimoreUnited States
- Division of Cardiovascular Medicine, Department of Medicine, University of Maryland School of MedicineBaltimoreUnited States
| | - Andrew Kyle Coleman
- Center for Biomedical Engineering and Technology, University of Maryland School of MedicineBaltimoreUnited States
- Department of Physiology, University of Marylan School of MedicineBaltimoreUnited States
| | - Nicolas Verhoeven
- Center for Biomedical Engineering and Technology, University of Maryland School of MedicineBaltimoreUnited States
- Department of Biochemistry and Molecular Biology, University of Maryland School of MedicineBaltimoreUnited States
| | - Carmen A Mannella
- Center for Biomedical Engineering and Technology, University of Maryland School of MedicineBaltimoreUnited States
- Department of Physiology, University of Marylan School of MedicineBaltimoreUnited States
| | - W Jonathan Lederer
- Center for Biomedical Engineering and Technology, University of Maryland School of MedicineBaltimoreUnited States
- Department of Physiology, University of Marylan School of MedicineBaltimoreUnited States
- Marlene and Stewart Greenebaum Comprehensive Cancer Center, University of Maryland Baltimore School of MedicineBaltimoreUnited States
| | - Liron Boyman
- Center for Biomedical Engineering and Technology, University of Maryland School of MedicineBaltimoreUnited States
- Department of Physiology, University of Marylan School of MedicineBaltimoreUnited States
- Marlene and Stewart Greenebaum Comprehensive Cancer Center, University of Maryland Baltimore School of MedicineBaltimoreUnited States
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18
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Song W, Qiu YT, Li XZ, Sun QY, Chen LN. 4-vinylcyclohexene diepoxide induces apoptosis by excessive reactive oxygen species and DNA damage in human ovarian granulosa cells. Toxicol In Vitro 2023; 91:105613. [PMID: 37182589 DOI: 10.1016/j.tiv.2023.105613] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2022] [Revised: 03/27/2023] [Accepted: 05/10/2023] [Indexed: 05/16/2023]
Abstract
4-Vinylcyclohexene diepoxide (VCD) is a hazardous industrial material which is widely used in the production of fragrances, rubber tires, antioxidants, pesticides, flame retardants and plasticizers. Previous studies have shown that exposure to VCD damages the female reproductive system, but the effects and mechanisms of VCD exposure on human granulosa cells are not reported. In this study, we used a human granulosa cell line (SVOG) to explore the effects of VCD exposure and found that VCD exposure had toxic effects on SVOG cells in vitro. VCD exposure led to excessive accumulation of intracellular ROS, caused DNA damage in cells, altered the expression of some key genes related with apoptosis and oxidative stress, and ultimately inhibited the proliferative capacity of granulosa cells, resulting in increased apoptosis. Overall, our findings provide solid evidence showing that VCD exposure produces severe damage to human granulosa cells, which is helpful for understanding the reproductive toxicity of VCD and etiology of infertility.
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Affiliation(s)
- Wei Song
- College of Life Sciences, Institute of Reproductive Sciences, Qingdao Agricultural University, Qingdao 266109, China; Guangzhou Key Laboratory of Metabolic Diseases and Reproductive Health, Guangdong-Hong Kong Metabolism & Reproduction Joint Laboratory, Reproductive Medicine Center, Guangdong Second Provincial General Hospital, Guangzhou 510317, China
| | - Yu-Ting Qiu
- College of Life Sciences, Institute of Reproductive Sciences, Qingdao Agricultural University, Qingdao 266109, China
| | - Xiao-Zhen Li
- College of Life Sciences, Institute of Reproductive Sciences, Qingdao Agricultural University, Qingdao 266109, China; Guangzhou Key Laboratory of Metabolic Diseases and Reproductive Health, Guangdong-Hong Kong Metabolism & Reproduction Joint Laboratory, Reproductive Medicine Center, Guangdong Second Provincial General Hospital, Guangzhou 510317, China
| | - Qing-Yuan Sun
- Guangzhou Key Laboratory of Metabolic Diseases and Reproductive Health, Guangdong-Hong Kong Metabolism & Reproduction Joint Laboratory, Reproductive Medicine Center, Guangdong Second Provincial General Hospital, Guangzhou 510317, China
| | - Lei-Ning Chen
- Guangzhou Key Laboratory of Metabolic Diseases and Reproductive Health, Guangdong-Hong Kong Metabolism & Reproduction Joint Laboratory, Reproductive Medicine Center, Guangdong Second Provincial General Hospital, Guangzhou 510317, China.
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19
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Yang L, Wang X, Zhao Y, Xue K, Liang J, Wang X, Deng J, Qi Z. An AIE luminogen targeting the endoplasmic reticulum inhibits cancer cell growth via multicellular organelle oxidative stress. Bioorg Chem 2023; 132:106361. [PMID: 36720178 DOI: 10.1016/j.bioorg.2023.106361] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2022] [Revised: 12/22/2022] [Accepted: 01/10/2023] [Indexed: 01/15/2023]
Abstract
Organelle-targeted photodynamic therapy has been increasingly investigated in recent decades, but little attention has been paid to the damage caused to other non-primary target organelles during the course of action, even though these non-primary target organelles may play a substantial role in inhibiting the growth of cancer cells. In this contribution, we report an AIE-type strong endoplasmic reticulum-targeted luminogen (MTOQS) with a distorted structure, which is efficient in producing ROS both in cellular and non-cellular environment, causing an effective reduction of high levels of GSH and MDA in cancer cells through the efficient accumulation of intracellular ROS, and the levels of ATP, l-lactic acid, anti-apoptotic factor Bcl-2 and apoptotic protein caspase-3 were determined. Through the identification of these markers, it was evidenced that MTOQS-induced dual organelle oxidative stress could diminish the degree of oxidative phosphorylation and glycolysis in cancer cells and trigger an alteration in the culture environment of cancer cells, while causing damage to the endoplasmic reticulum and mitochondria through multiorganelle oxidative stress, turning on the pathway of apoptosis and consequently driving cancer cells to apoptosis.
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Affiliation(s)
- Li Yang
- School of Chemistry and Chemical Engineering, Southeast University, Nanjing, Jiangsu 211189, PR China
| | - Xing Wang
- School of Chemistry and Chemical Engineering, Southeast University, Nanjing, Jiangsu 211189, PR China
| | - Yongfei Zhao
- School of Chemistry and Chemical Engineering, Southeast University, Nanjing, Jiangsu 211189, PR China
| | - Ke Xue
- School of Chemistry and Chemical Engineering, Southeast University, Nanjing, Jiangsu 211189, PR China
| | - Jiankang Liang
- School of Chemistry and Chemical Engineering, Southeast University, Nanjing, Jiangsu 211189, PR China
| | - Xiaohan Wang
- School of Chemistry and Chemical Engineering, Southeast University, Nanjing, Jiangsu 211189, PR China
| | - Jing Deng
- School of Chemistry and Chemical Engineering, Southeast University, Nanjing, Jiangsu 211189, PR China
| | - Zhengjian Qi
- School of Chemistry and Chemical Engineering, Southeast University, Nanjing, Jiangsu 211189, PR China.
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20
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Nesterov SV, Yaguzhinsky LS, Vasilov RG, Kadantsev VN, Goltsov AN. Contribution of the Collective Excitations to the Coupled Proton and Energy Transport along Mitochondrial Cristae Membrane in Oxidative Phosphorylation System. ENTROPY (BASEL, SWITZERLAND) 2022; 24:1813. [PMID: 36554218 PMCID: PMC9778164 DOI: 10.3390/e24121813] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/16/2022] [Revised: 12/06/2022] [Accepted: 12/09/2022] [Indexed: 06/17/2023]
Abstract
The results of many experimental and theoretical works indicate that after transport of protons across the mitochondrial inner membrane (MIM) in the oxidative phosphorylation (OXPHOS) system, they are retained on the membrane-water interface in nonequilibrium state with free energy excess due to low proton surface-to-bulk release. This well-established phenomenon suggests that proton trapping on the membrane interface ensures vectorial lateral transport of protons from proton pumps to ATP synthases (proton acceptors). Despite the key role of the proton transport in bioenergetics, the molecular mechanism of proton transfer in the OXPHOS system is not yet completely established. Here, we developed a dynamics model of long-range transport of energized protons along the MIM accompanied by collective excitation of localized waves propagating on the membrane surface. Our model is based on the new data on the macromolecular organization of the OXPHOS system showing the well-ordered structure of respirasomes and ATP synthases on the cristae membrane folds. We developed a two-component dynamics model of the proton transport considering two coupled subsystems: the ordered hydrogen bond (HB) chain of water molecules and lipid headgroups of MIM. We analytically obtained a two-component soliton solution in this model, which describes the motion of the proton kink, corresponding to successive proton hops in the HB chain, and coherent motion of a compression soliton in the chain of lipid headgroups. The local deformation in a soliton range facilitates proton jumps due to water molecules approaching each other in the HB chain. We suggested that the proton-conducting structures formed along the cristae membrane surface promote direct lateral proton transfer in the OXPHOS system. Collective excitations at the water-membrane interface in a form of two-component soliton ensure the coupled non-dissipative transport of charge carriers and elastic energy of MIM deformation to ATP synthases that may be utilized in ATP synthesis providing maximal efficiency in mitochondrial bioenergetics.
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Affiliation(s)
- Semen V. Nesterov
- Kurchatov Complex of NBICS-Technologies, National Research Center Kurchatov Institute, 123182 Moscow, Russia
- Research Center for Molecular Mechanisms of Aging and Age-Related Diseases, Moscow Institute of Physics and Technology, 141701 Dolgoprudny, Russia
| | - Lev S. Yaguzhinsky
- Research Center for Molecular Mechanisms of Aging and Age-Related Diseases, Moscow Institute of Physics and Technology, 141701 Dolgoprudny, Russia
- Department of Bioenergetics, Institute of Cytochemistry and Molecular Pharmacology, 115404 Moscow, Russia
- Belozersky Research Institute for Physico-Chemical Biology, Lomonosov Moscow State University, 119992 Moscow, Russia
| | - Raif G. Vasilov
- Kurchatov Complex of NBICS-Technologies, National Research Center Kurchatov Institute, 123182 Moscow, Russia
| | - Vasiliy N. Kadantsev
- Institute for Artificial Intelligence, Russian Technological University (MIREA), 119454 Moscow, Russia
| | - Alexey N. Goltsov
- Institute for Artificial Intelligence, Russian Technological University (MIREA), 119454 Moscow, Russia
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21
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Prola A, Pilot-Storck F. Cardiolipin Alterations during Obesity: Exploring Therapeutic Opportunities. BIOLOGY 2022; 11:1638. [PMID: 36358339 PMCID: PMC9687765 DOI: 10.3390/biology11111638] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Revised: 10/31/2022] [Accepted: 11/03/2022] [Indexed: 08/13/2023]
Abstract
Cardiolipin is a specific phospholipid of the mitochondrial inner membrane that participates in many aspects of its organization and function, hence promoting proper mitochondrial ATP production. Here, we review recent data that have investigated alterations of cardiolipin in different tissues in the context of obesity and the related metabolic syndrome. Data relating perturbations of cardiolipin content or composition are accumulating and suggest their involvement in mitochondrial dysfunction in tissues from obese patients. Conversely, cardiolipin modulation is a promising field of investigation in a search for strategies for obesity management. Several ways to restore cardiolipin content, composition or integrity are emerging and may contribute to the improvement of mitochondrial function in tissues facing excessive fat storage. Inversely, reduction of mitochondrial efficiency in a controlled way may increase energy expenditure and help fight against obesity and in this perspective, several options aim at targeting cardiolipin to achieve a mild reduction of mitochondrial coupling. Far from being just a victim of the deleterious consequences of obesity, cardiolipin may ultimately prove to be a possible weapon to fight against obesity in the future.
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Affiliation(s)
- Alexandre Prola
- Department of Cell Physiology and Metabolism, Faculty of Medicine, University of Geneva, 1211 Geneva, Switzerland
| | - Fanny Pilot-Storck
- Team Relaix, INSERM, IMRB, Université Paris-Est Créteil, F-94010 Créteil, France
- EnvA, IMRB, F-94700 Maisons-Alfort, France
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22
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Fei J, Li J. Advance in ATP-involved Active Self-assembled Systems. Curr Opin Colloid Interface Sci 2022. [DOI: 10.1016/j.cocis.2022.101647] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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23
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Loh D, Reiter RJ. Melatonin: Regulation of Viral Phase Separation and Epitranscriptomics in Post-Acute Sequelae of COVID-19. Int J Mol Sci 2022; 23:8122. [PMID: 35897696 PMCID: PMC9368024 DOI: 10.3390/ijms23158122] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2022] [Revised: 07/09/2022] [Accepted: 07/20/2022] [Indexed: 01/27/2023] Open
Abstract
The relentless, protracted evolution of the SARS-CoV-2 virus imposes tremendous pressure on herd immunity and demands versatile adaptations by the human host genome to counter transcriptomic and epitranscriptomic alterations associated with a wide range of short- and long-term manifestations during acute infection and post-acute recovery, respectively. To promote viral replication during active infection and viral persistence, the SARS-CoV-2 envelope protein regulates host cell microenvironment including pH and ion concentrations to maintain a high oxidative environment that supports template switching, causing extensive mitochondrial damage and activation of pro-inflammatory cytokine signaling cascades. Oxidative stress and mitochondrial distress induce dynamic changes to both the host and viral RNA m6A methylome, and can trigger the derepression of long interspersed nuclear element 1 (LINE1), resulting in global hypomethylation, epigenetic changes, and genomic instability. The timely application of melatonin during early infection enhances host innate antiviral immune responses by preventing the formation of "viral factories" by nucleocapsid liquid-liquid phase separation that effectively blockades viral genome transcription and packaging, the disassembly of stress granules, and the sequestration of DEAD-box RNA helicases, including DDX3X, vital to immune signaling. Melatonin prevents membrane depolarization and protects cristae morphology to suppress glycolysis via antioxidant-dependent and -independent mechanisms. By restraining the derepression of LINE1 via multifaceted strategies, and maintaining the balance in m6A RNA modifications, melatonin could be the quintessential ancient molecule that significantly influences the outcome of the constant struggle between virus and host to gain transcriptomic and epitranscriptomic dominance over the host genome during acute infection and PASC.
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Affiliation(s)
- Doris Loh
- Independent Researcher, Marble Falls, TX 78654, USA;
| | - Russel J. Reiter
- Department of Cell Systems and Anatomy, UT Health San Antonio, San Antonio, TX 78229, USA
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24
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Gottschalk B, Koshenov Z, Waldeck-Weiermair M, Radulović S, Oflaz FE, Hirtl M, Bachkoenig OA, Leitinger G, Malli R, Graier WF. MICU1 controls spatial membrane potential gradients and guides Ca 2+ fluxes within mitochondrial substructures. Commun Biol 2022; 5:649. [PMID: 35778442 PMCID: PMC9249747 DOI: 10.1038/s42003-022-03606-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2021] [Accepted: 06/17/2022] [Indexed: 01/19/2023] Open
Abstract
Mitochondrial ultrastructure represents a pinnacle of form and function, with the inner mitochondrial membrane (IMM) forming isolated pockets of cristae membrane (CM), separated from the inner-boundary membrane (IBM) by cristae junctions (CJ). Applying structured illumination and electron microscopy, a novel and fundamental function of MICU1 in mediating Ca2+ control over spatial membrane potential gradients (SMPGs) between CM and IMS was identified. We unveiled alterations of SMPGs by transient CJ openings when Ca2+ binds to MICU1 resulting in spatial cristae depolarization. This Ca2+/MICU1-mediated plasticity of the CJ further provides the mechanistic bedrock of the biphasic mitochondrial Ca2+ uptake kinetics via the mitochondrial Ca2+ uniporter (MCU) during intracellular Ca2+ release: Initially, high Ca2+ opens CJ via Ca2+/MICU1 and allows instant Ca2+ uptake across the CM through constantly active MCU. Second, MCU disseminates into the IBM, thus establishing Ca2+ uptake across the IBM that circumvents the CM. Under the condition of MICU1 methylation by PRMT1 in aging or cancer, UCP2 that binds to methylated MICU1 destabilizes CJ, disrupts SMPGs, and facilitates fast Ca2+ uptake via the CM.
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Affiliation(s)
- Benjamin Gottschalk
- grid.11598.340000 0000 8988 2476Gottfried Schatz Research Center: Molecular Biology and Biochemistry, Medical University of Graz, Graz, Austria
| | - Zhanat Koshenov
- grid.11598.340000 0000 8988 2476Gottfried Schatz Research Center: Molecular Biology and Biochemistry, Medical University of Graz, Graz, Austria
| | - Markus Waldeck-Weiermair
- grid.11598.340000 0000 8988 2476Gottfried Schatz Research Center: Molecular Biology and Biochemistry, Medical University of Graz, Graz, Austria
| | - Snježana Radulović
- grid.11598.340000 0000 8988 2476Gottfried Schatz Research Center: Cell Biology, Histology and Embryology, Medical University of Graz, Graz, Austria
| | - Furkan E. Oflaz
- grid.11598.340000 0000 8988 2476Gottfried Schatz Research Center: Molecular Biology and Biochemistry, Medical University of Graz, Graz, Austria
| | - Martin Hirtl
- grid.11598.340000 0000 8988 2476Gottfried Schatz Research Center: Molecular Biology and Biochemistry, Medical University of Graz, Graz, Austria
| | - Olaf A. Bachkoenig
- grid.11598.340000 0000 8988 2476Gottfried Schatz Research Center: Molecular Biology and Biochemistry, Medical University of Graz, Graz, Austria
| | - Gerd Leitinger
- grid.11598.340000 0000 8988 2476Gottfried Schatz Research Center: Cell Biology, Histology and Embryology, Medical University of Graz, Graz, Austria
| | - Roland Malli
- grid.11598.340000 0000 8988 2476Gottfried Schatz Research Center: Molecular Biology and Biochemistry, Medical University of Graz, Graz, Austria ,grid.452216.6BioTechMed Graz, Graz, Austria
| | - Wolfgang F. Graier
- grid.11598.340000 0000 8988 2476Gottfried Schatz Research Center: Molecular Biology and Biochemistry, Medical University of Graz, Graz, Austria ,grid.452216.6BioTechMed Graz, Graz, Austria
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25
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Romero-Morales AI, Gama V. Revealing the Impact of Mitochondrial Fitness During Early Neural Development Using Human Brain Organoids. Front Mol Neurosci 2022; 15:840265. [PMID: 35571368 PMCID: PMC9102998 DOI: 10.3389/fnmol.2022.840265] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Accepted: 04/04/2022] [Indexed: 11/13/2022] Open
Abstract
Mitochondrial homeostasis -including function, morphology, and inter-organelle communication- provides guidance to the intrinsic developmental programs of corticogenesis, while also being responsive to environmental and intercellular signals. Two- and three-dimensional platforms have become useful tools to interrogate the capacity of cells to generate neuronal and glia progeny in a background of metabolic dysregulation, but the mechanistic underpinnings underlying the role of mitochondria during human neurogenesis remain unexplored. Here we provide a concise overview of cortical development and the use of pluripotent stem cell models that have contributed to our understanding of mitochondrial and metabolic regulation of early human brain development. We finally discuss the effects of mitochondrial fitness dysregulation seen under stress conditions such as metabolic dysregulation, absence of developmental apoptosis, and hypoxia; and the avenues of research that can be explored with the use of brain organoids.
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Affiliation(s)
| | - Vivian Gama
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN, United States
- Vanderbilt Center for Stem Cell Biology, Vanderbilt University, Nashville, TN, United States
- Vanderbilt Brain Institute, Vanderbilt University, Nashville, TN, United States
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26
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Mechanistic Insights of Mitochondrial Dysfunction in Amyotrophic Lateral Sclerosis: An Update on a Lasting Relationship. Metabolites 2022; 12:metabo12030233. [PMID: 35323676 PMCID: PMC8951432 DOI: 10.3390/metabo12030233] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Revised: 03/07/2022] [Accepted: 03/08/2022] [Indexed: 02/01/2023] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterized by progressive loss of the upper and lower motor neurons. Despite the increasing effort in understanding the etiopathology of ALS, it still remains an obscure disease, and no therapies are currently available to halt its progression. Following the discovery of the first gene associated with familial forms of ALS, Cu–Zn superoxide dismutase, it appeared evident that mitochondria were key elements in the onset of the pathology. However, as more and more ALS-related genes were discovered, the attention shifted from mitochondria impairment to other biological functions such as protein aggregation and RNA metabolism. In recent years, mitochondria have again earned central, mechanistic roles in the pathology, due to accumulating evidence of their derangement in ALS animal models and patients, often resulting in the dysregulation of the energetic metabolism. In this review, we first provide an update of the last lustrum on the molecular mechanisms by which the most well-known ALS-related proteins affect mitochondrial functions and cellular bioenergetics. Next, we focus on evidence gathered from human specimens and advance the concept of a cellular-specific mitochondrial “metabolic threshold”, which may appear pivotal in ALS pathogenesis.
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27
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Zhang M, Zhang L, Guo R, Xiao C, Yin J, Zhang S, Yang M. Structural basis for the catalytic activity of filamentous human serine beta-lactamase-like protein LACTB. Structure 2022; 30:685-696.e5. [PMID: 35247327 DOI: 10.1016/j.str.2022.02.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2021] [Revised: 11/16/2021] [Accepted: 02/07/2022] [Indexed: 01/10/2023]
Abstract
Serine beta-lactamase-like protein (LACTB) is a mammalian mitochondrial serine protease that can specifically hydrolyze peptide bonds adjacent to aspartic acid residues and is structurally related to prokaryotic penicillin-binding proteins. Here, we determined the cryoelectron microscopy structures of human LACTB (hLACTB) filaments from wild-type protein, a middle region deletion mutant, and in complex with the inhibitor Z-AAD-CMK at 3.0-, 3.1-, and 2.8-Å resolution, respectively. Structural analysis and activity assays revealed that three interfaces are required for the assembly of hLACTB filaments and that the formation of higher order helical structures facilitates its cleavage activity. Further structural and enzymatic analyses of middle region deletion constructs indicated that, while this region is necessary for substrate hydrolysis, it is not required for filament formation. Moreover, the inhibitor-bound structure showed that hLACTB may cleave peptide bonds adjacent to aspartic acid residues. These findings provide the structural basis underlying hLACTB catalytic activity.
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Affiliation(s)
- Minghui Zhang
- Ministry of Education Key Laboratory of Protein Science, Tsinghua-Peking Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Laixing Zhang
- Ministry of Education Key Laboratory of Protein Science, Tsinghua-Peking Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Runyu Guo
- Ministry of Education Key Laboratory of Protein Science, Tsinghua-Peking Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Chun Xiao
- Ministry of Education Key Laboratory of Protein Science, Tsinghua-Peking Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Jian Yin
- Ministry of Education Key Laboratory of Protein Science, Tsinghua-Peking Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Sensen Zhang
- Ministry of Education Key Laboratory of Protein Science, Tsinghua-Peking Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China.
| | - Maojun Yang
- Ministry of Education Key Laboratory of Protein Science, Tsinghua-Peking Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China; Cryo-EM Facility Center, Southern University of Science & Technology, Shenzhen 518055, Guangdong, China.
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28
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Bondar AN. Mechanisms of long-distance allosteric couplings in proton-binding membrane transporters. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2022; 128:199-239. [PMID: 35034719 DOI: 10.1016/bs.apcsb.2021.09.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
Membrane transporters that use proton binding and proton transfer for function couple local protonation change with changes in protein conformation and water dynamics. Changes of protein conformation might be required to allow transient formation of hydrogen-bond networks that bridge proton donor and acceptor pairs separated by long distances. Inter-helical hydrogen-bond networks adjust rapidly to protonation change, and ensure rapid response of the protein structure and dynamics. Membrane transporters with known three-dimensional structures and proton-binding groups inform on general principles of protonation-coupled protein conformational dynamics. Inter-helical hydrogen bond motifs between proton-binding carboxylate groups and a polar sidechain are observed in unrelated membrane transporters, suggesting common principles of coupling protonation change with protein conformational dynamics.
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Affiliation(s)
- Ana-Nicoleta Bondar
- University of Bucharest, Faculty of Physics, Măgurele, Romania; Forschungszentrum Jülich, Institute of Computational Biomedicine, Jülich, Germany.
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29
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Gottschalk B, Madreiter-Sokolowski CT, Graier WF. Cristae junction as a fundamental switchboard for mitochondrial ion signaling and bioenergetics. Cell Calcium 2022; 101:102517. [PMID: 34915234 DOI: 10.1016/j.ceca.2021.102517] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Accepted: 12/08/2021] [Indexed: 12/31/2022]
Abstract
OPA1 and MICU1 are both involved in the regulation of mitochondrial Ca2+ uptake and the stabilization of the cristae junction, which separates the inner mitochondrial membrane into the interboundary membrane and the cristae membrane. In this mini-review, we focus on the synergetic control of OPA1 and MICU1 on the cristae junction that serves as a fundamental regulator of multiple mitochondrial functions. In particular, we point to the critical role of an adaptive cristae junction permeability in mitochondrial Ca2+ signaling, spatial H+ gradients and mitochondrial membrane potential, metabolic activity, and apoptosis. These characteristics bear on a distinct localization of the oxidative phosphorylation machinery, the FoF1-ATPase, and mitochondrial Ca2+uniporter (MCU) within sections of the inner mitochondrial membrane isolated by the cristae junction and regulated by proteins like OPA1 and MICU1. We specifically focus on the impact of MICU1-regulated cristae junction on the activity and distribution of MCU within the complex ultrastructure of mitochondria.
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Affiliation(s)
- Benjamin Gottschalk
- Gottfried Schatz Research Center: Molecular Biology and Biochemistry, Medical University of Graz, Neue Stiftingtalstraße 6/6, Graz, 8010 Austria
| | - Corina T Madreiter-Sokolowski
- Gottfried Schatz Research Center: Molecular Biology and Biochemistry, Medical University of Graz, Neue Stiftingtalstraße 6/6, Graz, 8010 Austria
| | - Wolfgang F Graier
- Gottfried Schatz Research Center: Molecular Biology and Biochemistry, Medical University of Graz, Neue Stiftingtalstraße 6/6, Graz, 8010 Austria; BioTechMed, Graz.
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30
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Silverstein TP. The Proton in Biochemistry: Impacts on Bioenergetics, Biophysical Chemistry, and Bioorganic Chemistry. Front Mol Biosci 2021; 8:764099. [PMID: 34901158 PMCID: PMC8661011 DOI: 10.3389/fmolb.2021.764099] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Accepted: 10/11/2021] [Indexed: 11/13/2022] Open
Abstract
The proton is the smallest atomic particle, and in aqueous solution it is the smallest hydrated ion, having only two waters in its first hydration shell. In this article we survey key aspects of the proton in chemistry and biochemistry, starting with the definitions of pH and pK a and their application inside biological cells. This includes an exploration of pH in nanoscale spaces, distinguishing between bulk and interfacial phases. We survey the Eigen and Zundel models of the structure of the hydrated proton, and how these can be used to explain: a) the behavior of protons at the water-hydrophobic interface, and b) the extraordinarily high mobility of protons in bulk water via Grotthuss hopping, and inside proteins via proton wires. Lastly, we survey key aspects of the effect of proton concentration and proton transfer on biochemical reactions including ligand binding and enzyme catalysis, as well as pH effects on biochemical thermodynamics, including the Chemiosmotic Theory. We find, for example, that the spontaneity of ATP hydrolysis at pH ≥ 7 is not due to any inherent property of ATP (or ADP or phosphate), but rather to the low concentration of H+. Additionally, we show that acidification due to fermentation does not derive from the organic acid waste products, but rather from the proton produced by ATP hydrolysis.
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Affiliation(s)
- Todd P Silverstein
- Chemistry Department (emeritus), Willamette University, Salem, OR, United States
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31
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Rieger B, Arroum T, Borowski M, Villalta J, Busch KB. Mitochondrial F 1 F O ATP synthase determines the local proton motive force at cristae rims. EMBO Rep 2021; 22:e52727. [PMID: 34595823 PMCID: PMC8647149 DOI: 10.15252/embr.202152727] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Revised: 08/31/2021] [Accepted: 09/10/2021] [Indexed: 12/25/2022] Open
Abstract
The classical view of oxidative phosphorylation is that a proton motive force (PMF) generated by the respiratory chain complexes fuels ATP synthesis via ATP synthase. Yet, under glycolytic conditions, ATP synthase in its reverse mode also can contribute to the PMF. Here, we dissected these two functions of ATP synthase and the role of its inhibitory factor 1 (IF1) under different metabolic conditions. pH profiles of mitochondrial sub-compartments were recorded with high spatial resolution in live mammalian cells by positioning a pH sensor directly at ATP synthase's F1 and FO subunits, complex IV and in the matrix. Our results clearly show that ATP synthase activity substantially controls the PMF and that IF1 is essential under OXPHOS conditions to prevent reverse ATP synthase activity due to an almost negligible ΔpH. In addition, we show how this changes lateral, transmembrane, and radial pH gradients in glycolytic and respiratory cells.
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Affiliation(s)
- Bettina Rieger
- Institute of Molecular Cell BiologySchool of BiologyUniversity of MünsterMünsterGermany
| | - Tasnim Arroum
- Institute of Molecular Cell BiologySchool of BiologyUniversity of MünsterMünsterGermany
| | - Marie‐Theres Borowski
- Institute of Molecular Cell BiologySchool of BiologyUniversity of MünsterMünsterGermany
| | - Jimmy Villalta
- Institute of Molecular Cell BiologySchool of BiologyUniversity of MünsterMünsterGermany
| | - Karin B Busch
- Institute of Molecular Cell BiologySchool of BiologyUniversity of MünsterMünsterGermany
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32
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Iovine JC, Claypool SM, Alder NN. Mitochondrial compartmentalization: emerging themes in structure and function. Trends Biochem Sci 2021; 46:902-917. [PMID: 34244035 PMCID: PMC11008732 DOI: 10.1016/j.tibs.2021.06.003] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Revised: 05/26/2021] [Accepted: 06/04/2021] [Indexed: 11/27/2022]
Abstract
Within cellular structures, compartmentalization is the concept of spatial segregation of macromolecules, metabolites, and biochemical pathways. Therefore, this concept bridges organellar structure and function. Mitochondria are morphologically complex, partitioned into several subcompartments by a topologically elaborate two-membrane system. They are also dynamically polymorphic, undergoing morphogenesis events with an extent and frequency that is only now being appreciated. Thus, mitochondrial compartmentalization is something that must be considered both spatially and temporally. Here, we review new developments in how mitochondrial structure is established and regulated, the factors that underpin the distribution of lipids and proteins, and how they spatially demarcate locations of myriad mitochondrial processes. Consistent with its pre-eminence, disturbed mitochondrial compartmentalization contributes to the dysfunction associated with heritable and aging-related diseases.
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Affiliation(s)
- Joseph C Iovine
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT 06269, USA
| | - Steven M Claypool
- Department of Physiology, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Nathan N Alder
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT 06269, USA.
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33
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Pánek T, Eliáš M, Vancová M, Lukeš J, Hashimi H. Returning to the Fold for Lessons in Mitochondrial Crista Diversity and Evolution. Curr Biol 2021; 30:R575-R588. [PMID: 32428499 DOI: 10.1016/j.cub.2020.02.053] [Citation(s) in RCA: 47] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Cristae are infoldings of the mitochondrial inner membrane jutting into the organelle's innermost compartment from narrow stems at their base called crista junctions. They are emblematic of aerobic mitochondria, being the fabric for the molecular machinery driving cellular respiration. Electron microscopy revealed that diverse eukaryotes possess cristae of different shapes. Yet, crista diversity has not been systematically examined in light of our current knowledge about eukaryotic evolution. Since crista form and function are intricately linked, we take a holistic view of factors that may underlie both crista diversity and the adherence of cristae to a recognizable form. Based on electron micrographs of 226 species from all major lineages, we propose a rational crista classification system that postulates cristae as variations of two general morphotypes: flat and tubulo-vesicular. The latter is most prevalent and likely ancestral, but both morphotypes are found interspersed throughout the eukaryotic tree. In contrast, crista junctions are remarkably conserved, supporting their proposed role as diffusion barriers that sequester cristae contents. Since cardiolipin, ATP synthase dimers, the MICOS complex, and dynamin-like Opa1/Mgm1 are known to be involved in shaping cristae, we examined their variation in the context of crista diversity. Moreover, we have identified both commonalities and differences that may collectively be manifested as diverse variations of crista form and function.
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Affiliation(s)
- Tomáš Pánek
- Department of Biology and Ecology, Faculty of Science, University of Ostrava, Ostrava 710 00, Czech Republic
| | - Marek Eliáš
- Department of Biology and Ecology, Faculty of Science, University of Ostrava, Ostrava 710 00, Czech Republic
| | - Marie Vancová
- Institute of Parasitology, Biology Center, Czech Academy of Sciences and Faculty of Science, University of South Bohemia, České Budějovice 370 05, Czech Republic
| | - Julius Lukeš
- Institute of Parasitology, Biology Center, Czech Academy of Sciences and Faculty of Science, University of South Bohemia, České Budějovice 370 05, Czech Republic
| | - Hassan Hashimi
- Institute of Parasitology, Biology Center, Czech Academy of Sciences and Faculty of Science, University of South Bohemia, České Budějovice 370 05, Czech Republic.
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34
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Protein Supercomplex Recording in Living Cells Via Position-Specific Fluorescence Lifetime Sensors. Methods Mol Biol 2021; 2275:301-314. [PMID: 34118046 DOI: 10.1007/978-1-0716-1262-0_19] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Our group has previously established a strategy utilizing fluorescence lifetime probes to image membrane protein supercomplex (SC) formation in situ. We showed that a probe at the interface between individual mitochondrial respiratory complexes exhibits a decreased fluorescence lifetime when a supercomplex is formed. This is caused by electrostatic interactions with the adjacent proteins. Fluorescence lifetime imaging microscopy (FLIM) records the resulting decrease of the lifetime of the SC-probe. Here we present the details of our method for performing SC-FLIM, including the evaluation of fluorescence lifetimes from the FLIM images. To validate the feasibility of the technique for monitoring adaptive SC formation, we compare data obtained under different metabolic conditions. The results confirm that SC formation is dynamic.
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35
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The human cytomegalovirus protein pUL13 targets mitochondrial cristae architecture to increase cellular respiration during infection. Proc Natl Acad Sci U S A 2021; 118:2101675118. [PMID: 34344827 DOI: 10.1073/pnas.2101675118] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Viruses modulate mitochondrial processes during infection to increase biosynthetic precursors and energy output, fueling virus replication. In a surprising fashion, although it triggers mitochondrial fragmentation, the prevalent pathogen human cytomegalovirus (HCMV) increases mitochondrial metabolism through a yet-unknown mechanism. Here, we integrate molecular virology, metabolic assays, quantitative proteomics, and superresolution confocal microscopy to define this mechanism. We establish that the previously uncharacterized viral protein pUL13 is required for productive HCMV replication, targets the mitochondria, and functions to increase oxidative phosphorylation during infection. We demonstrate that pUL13 forms temporally tuned interactions with the mitochondrial contact site and cristae organizing system (MICOS) complex, a critical regulator of cristae architecture and electron transport chain (ETC) function. Stimulated emission depletion superresolution microscopy shows that expression of pUL13 alters cristae architecture. Indeed, using live-cell Seahorse assays, we establish that pUL13 alone is sufficient to increase cellular respiration, not requiring the presence of other viral proteins. Our findings address the outstanding question of how HCMV targets mitochondria to increase bioenergetic output and expands the knowledge of the intricate connection between mitochondrial architecture and ETC function.
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36
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Lee JW. Mitochondrial energetics with transmembrane electrostatically localized protons: do we have a thermotrophic feature? Sci Rep 2021; 11:14575. [PMID: 34272427 PMCID: PMC8285424 DOI: 10.1038/s41598-021-93853-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2021] [Accepted: 06/07/2021] [Indexed: 01/24/2023] Open
Abstract
Transmembrane electrostatically localized protons (TELP) theory has been recently recognized as an important addition over the classic Mitchell's chemiosmosis; thus, the proton motive force (pmf) is largely contributed from TELP near the membrane. As an extension to this theory, a novel phenomenon of mitochondrial thermotrophic function is now characterized by biophysical analyses of pmf in relation to the TELP concentrations at the liquid-membrane interface. This leads to the conclusion that the oxidative phosphorylation also utilizes environmental heat energy associated with the thermal kinetic energy (kBT) of TELP in mitochondria. The local pmf is now calculated to be in a range from 300 to 340 mV while the classic pmf (which underestimates the total pmf) is in a range from 60 to 210 mV in relation to a range of membrane potentials from 50 to 200 mV. Depending on TELP concentrations in mitochondria, this thermotrophic function raises pmf significantly by a factor of 2.6 to sixfold over the classic pmf. Therefore, mitochondria are capable of effectively utilizing the environmental heat energy with TELP for the synthesis of ATP, i.e., it can lock heat energy into the chemical form of energy for cellular functions.
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Affiliation(s)
- James Weifu Lee
- Department of Chemistry and Biochemistry, Old Dominion University, Norfolk, VA, 23529, USA.
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37
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Patil N, Bonneau S, Joubert F, Bitbol AF, Berthoumieux H. Mitochondrial cristae modeled as an out-of-equilibrium membrane driven by a proton field. Phys Rev E 2021; 102:022401. [PMID: 32942462 DOI: 10.1103/physreve.102.022401] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Accepted: 06/27/2020] [Indexed: 01/27/2023]
Abstract
As the places where most of the fuel of the cell, namely, ATP, is synthesized, mitochondria are crucial organelles in eukaryotic cells. The shape of the invaginations of the mitochondria inner membrane, known as a crista, has been identified as a signature of the energetic state of the organelle. However, the interplay between the rate of ATP synthesis and the crista shape remains unclear. In this work, we investigate the crista membrane deformations using a pH-dependent Helfrich model, maintained out of equilibrium by a diffusive flux of protons. This model gives rise to shape changes of a cylindrical invagination, in particular to the formation of necks between wider zones under variable, and especially oscillating, proton flux.
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Affiliation(s)
- Nirbhay Patil
- Laboratoire de Physique Théorique de la Matière Condensée (LPTMC, UMR 7600), Sorbonne Université, CNRS, F-75005 Paris, France.,Laboratoire Jean Perrin (UMR 8237), Institut de Biologie Paris-Seine, Sorbonne Université, CNRS, F-75005 Paris, France
| | - Stéphanie Bonneau
- Laboratoire Jean Perrin (UMR 8237), Institut de Biologie Paris-Seine, Sorbonne Université, CNRS, F-75005 Paris, France
| | - Fréderic Joubert
- Laboratoire Jean Perrin (UMR 8237), Institut de Biologie Paris-Seine, Sorbonne Université, CNRS, F-75005 Paris, France
| | - Anne-Florence Bitbol
- Laboratoire Jean Perrin (UMR 8237), Institut de Biologie Paris-Seine, Sorbonne Université, CNRS, F-75005 Paris, France.,School of Life Sciences, Institute of Bioengineering, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Hélène Berthoumieux
- Laboratoire de Physique Théorique de la Matière Condensée (LPTMC, UMR 7600), Sorbonne Université, CNRS, F-75005 Paris, France
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38
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Aklima J, Onojima T, Kimura S, Umiuchi K, Shibata T, Kuraoka Y, Oie Y, Suganuma Y, Ohta Y. Effects of Matrix pH on Spontaneous Transient Depolarization and Reactive Oxygen Species Production in Mitochondria. Front Cell Dev Biol 2021; 9:692776. [PMID: 34277637 PMCID: PMC8278022 DOI: 10.3389/fcell.2021.692776] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Accepted: 05/26/2021] [Indexed: 01/28/2023] Open
Abstract
Reactive oxygen species (ROS) oxidize surrounding molecules and thus impair their functions. Since mitochondria are a major source of ROS, suppression of ROS overproduction in the mitochondria is important for cells. Spontaneous transient depolarization of individual mitochondria is a physiological phenomenon widely observed from plants to mammals. Mitochondrial uncoupling can reduce ROS production; therefore, it is conceivable that transient depolarization could reduce ROS production. However, transient depolarization has been observed with increased ROS production. Therefore, the exact contribution of transient depolarization to ROS production has not been elucidated. In this study, we examined how the spontaneous transient depolarization occurring in individual mitochondria affected ROS production. When the matrix pH increased after the addition of malate or exposure of the isolated mitochondria to a high-pH buffer, transient depolarization was stimulated. Similar stimulation by an increased matrix pH was also observed in the mitochondria in intact H9c2 cells. Modifying the mitochondrial membrane potential and matrix pH by adding K+ in the presence of valinomycin, a K+ ionophore, clarified that an increase in the matrix pH is a major cause of ROS generation. When we added ADP in the presence of oligomycin to suppress the transient depolarization without decreasing the matrix pH, we observed the suppression of mitochondrial respiration, increased matrix pH, and enhanced ROS production. Based on these results, we propose a model where spontaneous transient depolarization occurs during increased proton influx through proton channels opened by increased matrix pH, leading to the suppression of ROS production. This study improves our understanding of mitochondrial behavior.
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Affiliation(s)
- Jannatul Aklima
- Department of Biotechnology and Life Science, Tokyo University of Agriculture and Technology, Koganei, Japan.,Department of Biochemistry and Molecular Biology, University of Chittagong, Chittagong, Bangladesh
| | - Takumi Onojima
- Department of Biotechnology and Life Science, Tokyo University of Agriculture and Technology, Koganei, Japan
| | - Sawako Kimura
- Department of Biotechnology and Life Science, Tokyo University of Agriculture and Technology, Koganei, Japan
| | - Kanji Umiuchi
- Department of Biotechnology and Life Science, Tokyo University of Agriculture and Technology, Koganei, Japan
| | - Takahiro Shibata
- Department of Biotechnology and Life Science, Tokyo University of Agriculture and Technology, Koganei, Japan
| | - Yusho Kuraoka
- Department of Biotechnology and Life Science, Tokyo University of Agriculture and Technology, Koganei, Japan
| | - Yoshiki Oie
- Department of Biotechnology and Life Science, Tokyo University of Agriculture and Technology, Koganei, Japan
| | - Yoshiki Suganuma
- Department of Biotechnology and Life Science, Tokyo University of Agriculture and Technology, Koganei, Japan
| | - Yoshihiro Ohta
- Department of Biotechnology and Life Science, Tokyo University of Agriculture and Technology, Koganei, Japan
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39
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Joubert F, Puff N. Mitochondrial Cristae Architecture and Functions: Lessons from Minimal Model Systems. MEMBRANES 2021; 11:membranes11070465. [PMID: 34201754 PMCID: PMC8306996 DOI: 10.3390/membranes11070465] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Revised: 06/17/2021] [Accepted: 06/18/2021] [Indexed: 12/23/2022]
Abstract
Mitochondria are known as the powerhouse of eukaryotic cells. Energy production occurs in specific dynamic membrane invaginations in the inner mitochondrial membrane called cristae. Although the integrity of these structures is recognized as a key point for proper mitochondrial function, less is known about the mechanisms at the origin of their plasticity and organization, and how they can influence mitochondria function. Here, we review the studies which question the role of lipid membrane composition based mainly on minimal model systems.
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Affiliation(s)
- Frédéric Joubert
- Laboratoire Jean Perrin, CNRS, Sorbonne Université, UMR 8237, 75005 Paris, France;
| | - Nicolas Puff
- Faculté des Sciences et Ingénierie, Sorbonne Université, UFR 925 Physique, 75005 Paris, France
- Laboratoire Matière et Systèmes Complexes (MSC), Université Paris Diderot-Paris 7, UMR 7057 CNRS, 75013 Paris, France
- Correspondence:
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40
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Capitanio G, Papa F, Papa S. The allosteric protein interactions in the proton-motive function of mammalian redox enzymes of the respiratory chain. Biochimie 2021; 189:1-12. [PMID: 34097987 DOI: 10.1016/j.biochi.2021.05.018] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Revised: 05/17/2021] [Accepted: 05/31/2021] [Indexed: 12/22/2022]
Abstract
Insight into mammalian respiratory complexes defines the role of allosteric protein interactions in their proton-motive activity. In cytochrome c oxidase (CxIV) conformational change of subunit I, caused by O2 binding to heme a32+-CuB+ and reduction, and stereochemical transitions coupled to oxidation/reduction of heme a and CuA, combined with electrostatic effects, determine the proton pumping activity. In ubiquinone-cytochrome c oxidoreductase (CxIII) conformational movement of Fe-S protein between cytochromes b and c1 is the key element of the proton-motive activity. In NADH-ubiquinone oxidoreductase (CxI) ubiquinone binding and reduction result in conformational changes of subunits in the quinone reaction structure which initiate proton pumping.
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Affiliation(s)
- Giuseppe Capitanio
- Department of Basic Medical Sciences, Neurosciences and Sense Organs, University of Bari "Aldo Moro", 70124, Bari, Italy.
| | - Francesco Papa
- Department of Basic Medical Sciences, Neurosciences and Sense Organs, University of Bari "Aldo Moro", 70124, Bari, Italy.
| | - Sergio Papa
- Department of Basic Medical Sciences, Neurosciences and Sense Organs, University of Bari "Aldo Moro", 70124, Bari, Italy; Department of Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, 80121, Napoli, Italy.
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41
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Needs HI, Protasoni M, Henley JM, Prudent J, Collinson I, Pereira GC. Interplay between Mitochondrial Protein Import and Respiratory Complexes Assembly in Neuronal Health and Degeneration. Life (Basel) 2021; 11:432. [PMID: 34064758 PMCID: PMC8151517 DOI: 10.3390/life11050432] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Revised: 04/27/2021] [Accepted: 05/02/2021] [Indexed: 12/14/2022] Open
Abstract
The fact that >99% of mitochondrial proteins are encoded by the nuclear genome and synthesised in the cytosol renders the process of mitochondrial protein import fundamental for normal organelle physiology. In addition to this, the nuclear genome comprises most of the proteins required for respiratory complex assembly and function. This means that without fully functional protein import, mitochondrial respiration will be defective, and the major cellular ATP source depleted. When mitochondrial protein import is impaired, a number of stress response pathways are activated in order to overcome the dysfunction and restore mitochondrial and cellular proteostasis. However, prolonged impaired mitochondrial protein import and subsequent defective respiratory chain function contributes to a number of diseases including primary mitochondrial diseases and neurodegeneration. This review focuses on how the processes of mitochondrial protein translocation and respiratory complex assembly and function are interlinked, how they are regulated, and their importance in health and disease.
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Affiliation(s)
- Hope I. Needs
- School of Biochemistry, University of Bristol, Bristol BS8 1TD, UK; (H.I.N.); (J.M.H.)
| | - Margherita Protasoni
- Medical Research Council-Mitochondrial Biology Unit, University of Cambridge, Cambridge CB2 0XY, UK; (M.P.); (J.P.)
| | - Jeremy M. Henley
- School of Biochemistry, University of Bristol, Bristol BS8 1TD, UK; (H.I.N.); (J.M.H.)
- Centre for Neuroscience and Regenerative Medicine, Faculty of Science, University of Technology Sydney, Ultimo, NSW 2007, Australia
| | - Julien Prudent
- Medical Research Council-Mitochondrial Biology Unit, University of Cambridge, Cambridge CB2 0XY, UK; (M.P.); (J.P.)
| | - Ian Collinson
- School of Biochemistry, University of Bristol, Bristol BS8 1TD, UK; (H.I.N.); (J.M.H.)
| | - Gonçalo C. Pereira
- Medical Research Council-Mitochondrial Biology Unit, University of Cambridge, Cambridge CB2 0XY, UK; (M.P.); (J.P.)
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Organization of the Respiratory Supercomplexes in Cells with Defective Complex III: Structural Features and Metabolic Consequences. Life (Basel) 2021; 11:life11040351. [PMID: 33920624 PMCID: PMC8074069 DOI: 10.3390/life11040351] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Revised: 04/12/2021] [Accepted: 04/14/2021] [Indexed: 12/13/2022] Open
Abstract
The mitochondrial respiratory chain encompasses four oligomeric enzymatic complexes (complex I, II, III and IV) which, together with the redox carrier ubiquinone and cytochrome c, catalyze electron transport coupled to proton extrusion from the inner membrane. The protonmotive force is utilized by complex V for ATP synthesis in the process of oxidative phosphorylation. Respiratory complexes are known to coexist in the membrane as single functional entities and as supramolecular aggregates or supercomplexes (SCs). Understanding the assembly features of SCs has relevant biomedical implications because defects in a single protein can derange the overall SC organization and compromise the energetic function, causing severe mitochondrial disorders. Here we describe in detail the main types of SCs, all characterized by the presence of complex III. We show that the genetic alterations that hinder the assembly of Complex III, not just the activity, cause a rearrangement of the architecture of the SC that can help to preserve a minimal energetic function. Finally, the major metabolic disturbances associated with severe SCs perturbation due to defective complex III are discussed along with interventions that may circumvent these deficiencies.
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Kell DB. A protet-based, protonic charge transfer model of energy coupling in oxidative and photosynthetic phosphorylation. Adv Microb Physiol 2021; 78:1-177. [PMID: 34147184 DOI: 10.1016/bs.ampbs.2021.01.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Textbooks of biochemistry will explain that the otherwise endergonic reactions of ATP synthesis can be driven by the exergonic reactions of respiratory electron transport, and that these two half-reactions are catalyzed by protein complexes embedded in the same, closed membrane. These views are correct. The textbooks also state that, according to the chemiosmotic coupling hypothesis, a (or the) kinetically and thermodynamically competent intermediate linking the two half-reactions is the electrochemical difference of protons that is in equilibrium with that between the two bulk phases that the coupling membrane serves to separate. This gradient consists of a membrane potential term Δψ and a pH gradient term ΔpH, and is known colloquially as the protonmotive force or pmf. Artificial imposition of a pmf can drive phosphorylation, but only if the pmf exceeds some 150-170mV; to achieve in vivo rates the imposed pmf must reach 200mV. The key question then is 'does the pmf generated by electron transport exceed 200mV, or even 170mV?' The possibly surprising answer, from a great many kinds of experiment and sources of evidence, including direct measurements with microelectrodes, indicates it that it does not. Observable pH changes driven by electron transport are real, and they control various processes; however, compensating ion movements restrict the Δψ component to low values. A protet-based model, that I outline here, can account for all the necessary observations, including all of those inconsistent with chemiosmotic coupling, and provides for a variety of testable hypotheses by which it might be refined.
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Affiliation(s)
- Douglas B Kell
- Department of Biochemistry and Systems Biology, Institute of Systems, Molecular and Integrative, Biology, University of Liverpool, Liverpool, United Kingdom; The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Lyngby, Denmark.
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Afzal N, Lederer WJ, Jafri MS, Mannella CA. Effect of crista morphology on mitochondrial ATP output: A computational study. Curr Res Physiol 2021; 4:163-176. [PMID: 34396153 PMCID: PMC8360328 DOI: 10.1016/j.crphys.2021.03.005] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
Abstract
Folding of the mitochondrial inner membrane (IM) into cristae greatly increases the ATP-generating surface area, S IM, per unit volume but also creates diffusional bottlenecks that could limit reaction rates inside mitochondria. This study explores possible effects of inner membrane folding on mitochondrial ATP output, using a mathematical model for energy metabolism developed by the Jafri group and two- and three-dimensional spatial models for mitochondria, implemented on the Virtual Cell platform. Simulations demonstrate that cristae are micro-compartments functionally distinct from the cytosol. At physiological steady states, standing gradients of ADP form inside cristae that depend on the size and shape of the compartments, and reduce local flux (rate per unit area) of the adenine nucleotide translocase. This causes matrix ADP levels to drop, which in turn reduces the flux of ATP synthase. The adverse effects of membrane folding on reaction fluxes increase with crista length and are greater for lamellar than tubular crista. However, total ATP output per mitochondrion is the product of flux of ATP synthase and S IM which can be two-fold greater for mitochondria with lamellar than tubular cristae, resulting in greater ATP output for the former. The simulations also demonstrate the crucial role played by intracristal kinases (adenylate kinase, creatine kinase) in maintaining the energy advantage of IM folding.
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Affiliation(s)
- Nasrin Afzal
- Krasnow Institute for Advanced Study and School of Systems Biology, George Mason University, Fairfax, VA, 22030, USA
| | - W Jonathan Lederer
- Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, MD, 21201, USA.,Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
| | - M Saleet Jafri
- Krasnow Institute for Advanced Study and School of Systems Biology, George Mason University, Fairfax, VA, 22030, USA.,Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
| | - Carmen A Mannella
- Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, MD, 21201, USA.,Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
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Raven JA. Determinants, and implications, of the shape and size of thylakoids and cristae. JOURNAL OF PLANT PHYSIOLOGY 2021; 257:153342. [PMID: 33385618 DOI: 10.1016/j.jplph.2020.153342] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Revised: 11/25/2020] [Accepted: 12/08/2020] [Indexed: 06/12/2023]
Abstract
Thylakoids are flattened sacs isolated from other membranes; cristae are attached to the rest of the inner mitochondrial membrane by the crista junction, but the crista lumen is separated from the intermembrane space. The shape of thylakoids and cristae involves membranes with small (5-30 nm) radii of curvature. While the mechanism of curvature is not entirely clear, it seems to be largely a function of Curt proteins in thylakoids and Mitochondrial Organising Site and Crista Organising Centre proteins and oligomeric FOF1 ATP synthase in cristae. A subordinate, or minimal, role is attributable to lipids with areas of their head group area greater (convex leaflet) or smaller (concave leaflet) than the area of the lipid tail; examples of the latter group are monogalactosyldiglyceride in thylakoids and cardiolipin in cristae. The volume per unit area on the lumen side of the membrane is less than that of the chloroplast stroma or cyanobacterial cytosol for thylakoids, and mitochondrial matrix for cristae. A low volume per unit area of thylakoids and cristae means a small lumen width that is the average of wider spaces between lipid parts of the membranes and the narrower gaps dominated by extra-membrane components of transmembrane proteins. These structural constraints have important implications for the movement of the electron carriers plastocyanin and cytochrome c6 (thylakoids) and cytochrome c (cristae) and hence the separation of the membrane-associated electron donors to, and electron acceptors from, these water-soluble electron carriers. The donor/acceptor pairs, are the cytochrome fb6Fenh complex and P700+ in thylakoids, and Complex III and Complex IV of cristae. The other energy flux parallel to the membranes is that of the proton motive force generated by redox-powered H+ pumps into the lumen to the proton motive force use in ATP synthesis by H+ flux from the lumen through the ATP synthase. For both the electron transport and proton motive force movement, concentration differences of reduced and oxidised electron carriers and protonated and deprotonated pH buffers are involved. The need for diffusion along a congested route of these energy transfer agents may limit the separation of sources and sinks parallel to the membranes of thylakoids and cristae.
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Affiliation(s)
- John A Raven
- Division of Plant Science, University of Dundee at the James Hutton Institute, Invergowrie, Dundee, DD2 5DA, UK; University of Technology, Sydney, Climate Change Cluster, Faculty of Science, Sydney, Ultimo, NSW, 2007, Australia; School of Biological Sciences, University of Western Australia, Crawley, WA, 6009, Australia.
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Mühleip A, Kock Flygaard R, Ovciarikova J, Lacombe A, Fernandes P, Sheiner L, Amunts A. ATP synthase hexamer assemblies shape cristae of Toxoplasma mitochondria. Nat Commun 2021; 12:120. [PMID: 33402698 PMCID: PMC7785744 DOI: 10.1038/s41467-020-20381-z] [Citation(s) in RCA: 52] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Accepted: 11/30/2020] [Indexed: 01/29/2023] Open
Abstract
Mitochondrial ATP synthase plays a key role in inducing membrane curvature to establish cristae. In Apicomplexa causing diseases such as malaria and toxoplasmosis, an unusual cristae morphology has been observed, but its structural basis is unknown. Here, we report that the apicomplexan ATP synthase assembles into cyclic hexamers, essential to shape their distinct cristae. Cryo-EM was used to determine the structure of the hexamer, which is held together by interactions between parasite-specific subunits in the lumenal region. Overall, we identified 17 apicomplexan-specific subunits, and a minimal and nuclear-encoded subunit-a. The hexamer consists of three dimers with an extensive dimer interface that includes bound cardiolipins and the inhibitor IF1. Cryo-ET and subtomogram averaging revealed that hexamers arrange into ~20-megadalton pentagonal pyramids in the curved apical membrane regions. Knockout of the linker protein ATPTG11 resulted in the loss of pentagonal pyramids with concomitant aberrantly shaped cristae. Together, this demonstrates that the unique macromolecular arrangement is critical for the maintenance of cristae morphology in Apicomplexa.
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Affiliation(s)
- Alexander Mühleip
- Science for Life Laboratory, Department of Biochemistry and Biophysics, Stockholm University, 17165, Solna, Sweden
- Department of Medical Biochemistry and Biophysics, Karolinska Institute, 17177, Stockholm, Sweden
| | - Rasmus Kock Flygaard
- Science for Life Laboratory, Department of Biochemistry and Biophysics, Stockholm University, 17165, Solna, Sweden
- Department of Medical Biochemistry and Biophysics, Karolinska Institute, 17177, Stockholm, Sweden
| | - Jana Ovciarikova
- Wellcome Centre for Integrative Parasitology, University of Glasgow, Glasgow, UK
| | - Alice Lacombe
- Wellcome Centre for Integrative Parasitology, University of Glasgow, Glasgow, UK
| | - Paula Fernandes
- Science for Life Laboratory, Department of Biochemistry and Biophysics, Stockholm University, 17165, Solna, Sweden
- Department of Medical Biochemistry and Biophysics, Karolinska Institute, 17177, Stockholm, Sweden
- Wellcome Centre for Integrative Parasitology, University of Glasgow, Glasgow, UK
| | - Lilach Sheiner
- Wellcome Centre for Integrative Parasitology, University of Glasgow, Glasgow, UK.
| | - Alexey Amunts
- Science for Life Laboratory, Department of Biochemistry and Biophysics, Stockholm University, 17165, Solna, Sweden.
- Department of Medical Biochemistry and Biophysics, Karolinska Institute, 17177, Stockholm, Sweden.
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Prola A, Blondelle J, Vandestienne A, Piquereau J, Denis RGP, Guyot S, Chauvin H, Mourier A, Maurer M, Henry C, Khadhraoui N, Gallerne C, Molinié T, Courtin G, Guillaud L, Gressette M, Solgadi A, Dumont F, Castel J, Ternacle J, Demarquoy J, Malgoyre A, Koulmann N, Derumeaux G, Giraud MF, Joubert F, Veksler V, Luquet S, Relaix F, Tiret L, Pilot-Storck F. Cardiolipin content controls mitochondrial coupling and energetic efficiency in muscle. SCIENCE ADVANCES 2021; 7:7/1/eabd6322. [PMID: 33523852 PMCID: PMC7775760 DOI: 10.1126/sciadv.abd6322] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Accepted: 11/04/2020] [Indexed: 05/11/2023]
Abstract
Unbalanced energy partitioning participates in the rise of obesity, a major public health concern in many countries. Increasing basal energy expenditure has been proposed as a strategy to fight obesity yet raises efficiency and safety concerns. Here, we show that mice deficient for a muscle-specific enzyme of very-long-chain fatty acid synthesis display increased basal energy expenditure and protection against high-fat diet-induced obesity. Mechanistically, muscle-specific modulation of the very-long-chain fatty acid pathway was associated with a reduced content of the inner mitochondrial membrane phospholipid cardiolipin and a blunted coupling efficiency between the respiratory chain and adenosine 5'-triphosphate (ATP) synthase, which was restored by cardiolipin enrichment. Our study reveals that selective increase of lipid oxidative capacities in skeletal muscle, through the cardiolipin-dependent lowering of mitochondrial ATP production, provides an effective option against obesity at the whole-body level.
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Affiliation(s)
- Alexandre Prola
- Université Paris-Est Créteil, INSERM, IMRB, Team Relaix, F-94010 Créteil, France
- EnvA, IMRB, F-94700 Maisons-Alfort, France
- EFS, IMRB, F-94010 Créteil, France
| | - Jordan Blondelle
- Université Paris-Est Créteil, INSERM, IMRB, Team Relaix, F-94010 Créteil, France
- EnvA, IMRB, F-94700 Maisons-Alfort, France
- EFS, IMRB, F-94010 Créteil, France
| | - Aymeline Vandestienne
- Université Paris-Est Créteil, INSERM, IMRB, Team Relaix, F-94010 Créteil, France
- EnvA, IMRB, F-94700 Maisons-Alfort, France
- EFS, IMRB, F-94010 Créteil, France
| | - Jérôme Piquereau
- UMR-S 1180, INSERM, Université Paris-Sud, Université Paris-Saclay, F-92296 Châtenay-Malabry, France
| | | | - Stéphane Guyot
- Université Bourgogne Franche-Comté, AgroSup Dijon, PAM UMR A 02.102, F-21000 Dijon, France
| | - Hadrien Chauvin
- Université Paris-Est Créteil, INSERM, IMRB, Team Relaix, F-94010 Créteil, France
- EnvA, IMRB, F-94700 Maisons-Alfort, France
- EFS, IMRB, F-94010 Créteil, France
| | - Arnaud Mourier
- Université Bordeaux, CNRS, IBGC, UMR 5095, F-33000 Bordeaux, France
| | - Marie Maurer
- Université Paris-Est Créteil, INSERM, IMRB, Team Relaix, F-94010 Créteil, France
- EnvA, IMRB, F-94700 Maisons-Alfort, France
- EFS, IMRB, F-94010 Créteil, France
| | - Céline Henry
- PAPPSO, Université Paris-Saclay, INRAE, AgroParisTech, Micalis Institute, F-78350 Jouy-en-Josas, France
| | - Nahed Khadhraoui
- Université Paris-Est Créteil, INSERM, IMRB, Team Relaix, F-94010 Créteil, France
- EnvA, IMRB, F-94700 Maisons-Alfort, France
- EFS, IMRB, F-94010 Créteil, France
| | - Cindy Gallerne
- Université Paris-Est Créteil, INSERM, IMRB, Team Relaix, F-94010 Créteil, France
- EnvA, IMRB, F-94700 Maisons-Alfort, France
- EFS, IMRB, F-94010 Créteil, France
| | - Thibaut Molinié
- Université Bordeaux, CNRS, IBGC, UMR 5095, F-33000 Bordeaux, France
| | - Guillaume Courtin
- Université Paris-Est Créteil, INSERM, IMRB, Team Relaix, F-94010 Créteil, France
- EnvA, IMRB, F-94700 Maisons-Alfort, France
- EFS, IMRB, F-94010 Créteil, France
| | - Laurent Guillaud
- Université Paris-Est Créteil, INSERM, IMRB, Team Relaix, F-94010 Créteil, France
- EnvA, IMRB, F-94700 Maisons-Alfort, France
- EFS, IMRB, F-94010 Créteil, France
| | - Mélanie Gressette
- UMR-S 1180, INSERM, Université Paris-Sud, Université Paris-Saclay, F-92296 Châtenay-Malabry, France
| | - Audrey Solgadi
- UMS IPSIT, Université Paris-Saclay, F-92296 Châtenay-Malabry, France
| | - Florent Dumont
- UMS IPSIT, Université Paris-Saclay, F-92296 Châtenay-Malabry, France
| | - Julien Castel
- Université de Paris, BFA, UMR 8251, CNRS, F-75014 Paris, France
| | - Julien Ternacle
- Université Paris-Est Créteil, INSERM, IMRB, Team Derumeaux, F-94010 Creteil, France
| | - Jean Demarquoy
- Université Bourgogne Franche-Comté, AgroSup Dijon, PAM UMR A 02.102, F-21000 Dijon, France
| | - Alexandra Malgoyre
- Département Environnements Opérationnels, Unité de Physiologie des Exercices et Activités en Conditions Extrêmes, Institut de Recherche Biomédicale des Armées, F-91220 Brétigny-Sur-Orge, France
- LBEPS, Université Evry, IRBA, Université Paris-Saclay, F-91025 Evry, France
| | - Nathalie Koulmann
- Département Environnements Opérationnels, Unité de Physiologie des Exercices et Activités en Conditions Extrêmes, Institut de Recherche Biomédicale des Armées, F-91220 Brétigny-Sur-Orge, France
- LBEPS, Université Evry, IRBA, Université Paris-Saclay, F-91025 Evry, France
- École du Val de Grâce, Place Alphonse Laveran, F-75005 Paris, France
| | - Geneviève Derumeaux
- Université Paris-Est Créteil, INSERM, IMRB, Team Derumeaux, F-94010 Creteil, France
| | | | - Frédéric Joubert
- Laboratoire Jean Perrin, CNRS, Sorbonne Université, UMR 8237, Paris, F-75005, France
| | - Vladimir Veksler
- UMR-S 1180, INSERM, Université Paris-Sud, Université Paris-Saclay, F-92296 Châtenay-Malabry, France
| | - Serge Luquet
- Université de Paris, BFA, UMR 8251, CNRS, F-75014 Paris, France
| | - Frédéric Relaix
- Université Paris-Est Créteil, INSERM, IMRB, Team Relaix, F-94010 Créteil, France.
- EnvA, IMRB, F-94700 Maisons-Alfort, France
- EFS, IMRB, F-94010 Créteil, France
| | - Laurent Tiret
- Université Paris-Est Créteil, INSERM, IMRB, Team Relaix, F-94010 Créteil, France.
- EnvA, IMRB, F-94700 Maisons-Alfort, France
- EFS, IMRB, F-94010 Créteil, France
| | - Fanny Pilot-Storck
- Université Paris-Est Créteil, INSERM, IMRB, Team Relaix, F-94010 Créteil, France.
- EnvA, IMRB, F-94700 Maisons-Alfort, France
- EFS, IMRB, F-94010 Créteil, France
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Weissert V, Rieger B, Morris S, Arroum T, Psathaki OE, Zobel T, Perkins G, Busch KB. Inhibition of the mitochondrial ATPase function by IF1 changes the spatiotemporal organization of ATP synthase. BIOCHIMICA ET BIOPHYSICA ACTA. BIOENERGETICS 2021; 1862:148322. [PMID: 33065099 PMCID: PMC7718977 DOI: 10.1016/j.bbabio.2020.148322] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Revised: 09/11/2020] [Accepted: 09/29/2020] [Indexed: 01/20/2023]
Abstract
• Mitochondrial F1FO ATP synthase is the key enzyme for mitochondrial bioenergetics. Dimeric F1FO-ATP synthase, is preferentially located at the edges of the cristae and its oligomerization state determines mitochondrial ultrastructure. The ATP synthase inhibitor protein IF1 modulates not only ATP synthase activity but also regulates both the structure and function of mitochondria. In order to understand this in more detail, we have investigated the effect of IF1 on the spatiotemporal organization of the ATP synthase. Stable cell lines were generated that overexpressed IF1 and constitutively active IF1-H49K. The expression of IF1-H49K induced a change in the localization and mobility of the ATP synthase as analyzed by single molecule tracking and localization microscopy (TALM). In addition, the ultrastructure and function of mitochondria in cells with higher levels of active IF1 displayed a gradual alteration. In state III, cristae structures were significantly altered. The inhibition of the hydrolase activity of the F1FO-ATP synthase by IF1 together with altered inner mitochondrial membrane caused re-localization and altered mobility of the enzyme.
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Affiliation(s)
- Verena Weissert
- Center of Cellular Nanoanalytics, Integrated Bioimaging Facility, University of Osnabrück, 49076 Osnabrück, Lower Saxony, Germany
| | - Bettina Rieger
- Institute of Molecular Cell Biology, Department of Biology, University of Muenster, 48149 Muenster, Germany
| | - Silke Morris
- Institute of Molecular Cell Biology, Department of Biology, University of Muenster, 48149 Muenster, Germany
| | - Tasnim Arroum
- Institute of Molecular Cell Biology, Department of Biology, University of Muenster, 48149 Muenster, Germany
| | - Olympia Ekaterini Psathaki
- Center of Cellular Nanoanalytics, Integrated Bioimaging Facility, University of Osnabrück, 49076 Osnabrück, Lower Saxony, Germany
| | - Thomas Zobel
- Imaging Network, Cells in Motion Interfaculty Centre, University of Muenster, 48149 Muenster, Germany
| | - Guy Perkins
- National Center for Microscopy and Imaging Research, University of California, San Diego, CA, USA
| | - Karin B Busch
- Institute of Molecular Cell Biology, Department of Biology, University of Muenster, 48149 Muenster, Germany.
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49
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Nath S. Molecular-level understanding of biological energy coupling and transduction: Response to "Chemiosmotic misunderstandings". Biophys Chem 2020; 268:106496. [PMID: 33160142 DOI: 10.1016/j.bpc.2020.106496] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Revised: 10/06/2020] [Accepted: 10/27/2020] [Indexed: 02/08/2023]
Abstract
In a recent paper entitled "Chemiosmotic misunderstandings", it is claimed that "enough shortcomings in Mitchell's chemiosmotic theory have not been found and that a novel paradigm that offers at least as much explanatory power as chemiosmosis is not ready." This view is refuted by a wealth of molecular-level experimental data and strong new theoretical and computational evidence. It is shown that the chemiosmotic theory was beset with a large number of major shortcomings ever since the time when it was first proposed in the 1960s. These multiple shortcomings and flaws of chemiosmosis were repeatedly pointed out in incisive critiques by biochemical authorities of the late 20th century. All the shortcomings and flaws have been shown to be rectified by a quantitative, unified molecular-level theory that leads to a deeper and far more accurate understanding of biological energy coupling and ATP synthesis. The new theory is shown to be consistent with pioneering X-ray and cryo-EM structures and validated by state-of-the-art single-molecule techniques. Several new biochemical experimental tests are proposed and constructive ways for providing a revitalizing conceptual background and theory for integration of the available experimental information are suggested.
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Affiliation(s)
- Sunil Nath
- Department of Biochemical Engineering and Biotechnology, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India.
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Lee JW. Protonic conductor: better understanding neural resting and action potential. J Neurophysiol 2020; 124:1029-1044. [PMID: 32816602 DOI: 10.1152/jn.00281.2020] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
With the employment of the transmembrane electrostatic proton localization theory with a new membrane potential equation, neural resting and action potential is now much better understood as the voltage contributed by the localized protons/cations at a neural liquid- membrane interface. Accordingly, the neural resting/action potential is essentially a protonic/cationic membrane capacitor behavior. It is now understood with a newly formulated action potential equation: when action potential is <0 (negative number), the localized protons/cations charge density at the liquid-membrane interface along the periplasmic side is >0 (positive number); when the action potential is >0, the concentration of the localized protons and localized nonproton cations is <0, indicating a "depolarization" state. The nonlinear curve of the localized protons/cations charge density in the real-time domain of an action potential spike appears as an inverse mirror image to the action potential. The newly formulated action potential equation provides biophysical insights for neuron electrophysiology, which may represent a complementary development to the classic Goldman-Hodgkin-Katz equation. With the use of the action potential equation, the biological significance of axon myelination is now also elucidated as to provide protonic insulation and prevent any ions both inside and outside of the neuron from interfering with the action potential signal, so that the action potential can quickly propagate along the axon with minimal (e.g., 40 times less) energy requirement.NEW & NOTEWORTHY The newly formulated action potential equation provides biophysical insights for neuron electrophysiology, which may represent a complementary development to the classic Goldman-Hodgkin-Katz equation. The nonlinear curve of the localized protons/cations charge density in the real-time domain of an action potential spike appears as an inverse mirror image to the action potential. The biological significance of axon myelination is now elucidated as to provide protonic insulation and prevent any ions from interfering with action potential signal.
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Affiliation(s)
- James Weifu Lee
- Department of Chemistry & Biochemistry, Old Dominion University, Norfolk, Virginia
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